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ILLINOIS BIOLOGICAL 
MONOGRAPHS 


PUBLISHED QUARTERLY 
UNDER THE AUSPICES OF THE GRADUATE SCHOOL 
BY THE UNIVERSITY OF ILLINOIS 


VOLUME VIII 


Urbana, Illinois 


1923 


EDITORIAL COMMITTEE 


STEPHEN ALFRED FORBES 


HENRY BALDWIN WARD 


ce 
c< 
ce c 


WILLIAM TRELEASE 


u. sua 77 OY YL 


TABLE OF CONTENTS 


VOLUME VIII 

NUMBERS PAGES 
1. The head-capsule of Coleoptera. By F. S. Stickney. With 26 plates.... 1-104 

2. Comparative studies on certain features of Nematodes and their sig- 
nificance. By D. C. Hetherington. With 4 plates................. 105-166 

3. Parasitic fungi from British Guiana and Trinidad. By F. L. Stevens. 
RUNCREED ARPES OBS Nodak th ok Sal Page cael A Re Meer de einige oie MORO 167-242 

4. The external Morphology and Postembryology of Noctuid Larvae. By 
243-344 


Fe BaRipleye. With Splatest.:/cx ancy eects a eee areereteraeze 


ny 


Dacca 


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Shakeela 
Adige Ree | 


ae be Peet thi va Rl hulaicntiinn’ bin dain ‘eae 
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ILLINOIS BIOLOGICAL 
MONOGRAPHS 


Vol. VIII January, 1923 No. 1 


EDITORIAL COMMITTEE 


STEPHEN ALFRED FORBES WILLIAM TRELEASE 


HENRY BALDWIN WARD 


PUBLISHED UNDER THE 
AUSPICES OF THE GRADUATE SCHOOL BY 
THE UNIVERSITY OF ILLINOIS PRESS 


CopyricHT, 1923 By THE UNIVERSITY OF ILLINOIS 
DISTRIBUTED JUNE 20, 1923 


THE HEAD-CAPSULE OF COLEOPTERA 


WITH TWENTY-SIX PLATES 


BY 


FENNER SATTERTHWAITE STICKNEY 


Contributions from the : 
Entomological iaeeeatares a oe University of Illinois 
0. 


THESIS 


SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE 
DEGREE OF DOCTOR OF PHILOSOPHY IN ENTOMOLOGY IN THE 
GRADUATE SCHOOL OF THE UNIVERSITY OF ILLINOIS 


1921 


TABLE OF CONTENTS 


are TELSFC ETOCS Se Cys I eee a aoe ese Ree se i lsat chiens EM if 
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IN ee en he LNs penn AN lego A oy an arg Ai BN) pal NOIDA a6 408.9 16 
eUMORA EAMES rx ay SG as, Zeke ion ae a aiako tc ee ae PR eee 17 
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MRNA RA Or) esi rc lac 8s ME va ave ea el stake Ndi s mamta © Sloe @ ea 21 
(|e Ses Rie ae nit er UAE ae Pt Si A eR ND Beas: 21 
EMME Pe he en a kU RELA reeset state Ware Wn ce ei wley aed eee aaa ae 22 
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VEGETAL EO LORIUEAT ren re ter ieee ea aii esrel te Ainag eed hie tel ebtoe oh sbens bata olie es trate 37 
5 Se TS AAR OR el We OR a oe Pr SO a ea er se 37 
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SLLEEE TTT Ae NPA Sy eS I Ue ee Ae RU Heme emai eta cRecY 48 


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7] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 7 


INTRODUCTION 


LeConte and Horn published in 1883 a classification of the Coleoptera 
that has stood the wear of time remarkably well. Since then, however, 
a number of new classifications have been proposed: Lameere (1900 and 
1903), Ganglbauer (1892-1904), Handlirsch (1906-1908), Kolbe (1901, 
1908, and 1911), Sharp (1909), and Gahan (1911), all of which differ more 
or less seriously in one way or another, and show, for one thing, the need 
of further comparative morphological data, which is, of course, indispensa- 
ble to the building of any thorough classification. Leng’s recent catalogue 
(1920) also emphasizes this need. 

A review of the literature seems to show but few studies based on the 
comparative morphology of a comprehensive series of coleopterous fami- 
lies. A number of European workers have published comparative studies 
of the wings of Coleoptera, the most recent being by d’Orchymont (1920). 
Sharp and Muir (1912) and Muir (1918) have published the results of 
their investigations on the male geirital tube in Coleoptera. Various 
internal structures have been discussed-from time to time by a number 
of workers. Narrower in scope is the work’ of d’Orchymont (1916) on the 
classification of the Hydrophiloidea, based on’a study of both the adult 
and the larva. Hyslop (1917), Béving and Champlain (1920), Craighead 
(1920), and Gage (1920) have published papers on the comparative mor- 
phology of various families, based on a study of the larvae. There are prob- 
ably other comparative papers more or less extensive in scope, but I have 
not been able to find any such literature based on a study of the head- 
capsule, though Crampton (1917, 1920, and 1921) has included the discus- 
sion of the coleopterous head in papers not limited to a single order. The 
comparative morphology of the head-capsule of some other orders, how- 
ever, has been investigated: Peterson (1915) on the Thysanoptera, Peter- 
son (1916) on the Diptera, Yuasa (1920) on the Orthoptera, and Hoke 
(1923) on the Plecoptera. These simply draw attention to the need of 
such an investigation of the head-capsule of Coleoptera. 

With the broader vision in mind of a more satisfactory and natural 
classification of the Coleoptera, the following study on the comparative 
morphology of the head-capsule is offered. This study does not aim by 
any means to exhaust the subject. There have been too few species in- 
vestigated in each family to justify the making of any sweeping state- 
ments. This study can simply point out characteristic conditions of 
structures as found in the different species of the families studied, revealing, 


8 ILLINOIS BIOLOGICAL MONOGRAPHS [8 


therefore, inharmonies, and perhaps suggesting improvements on the pres- 
ent arrangement of the classification. 

In order to reach a correct estimate of the degree of specialization of 
the various parts of the head-capsule, an hypothetical type, representing 
a supposed primitive condition, has been constructed. The structure of 
this hypothetical type is based on the structure of the head-capsule of 
generalized insects and of generalized adult and larval Coleoptera. Each 
structure has been treated separately, starting from the hypothetical type. 
The submentum has been included in this study because of its bearing on 
certain developmental processes. All statements made refer to the species 
listed under “materials” only. The material studied was soaked in a 10% 
solution of potassium hydroxide until clarified, then washed in distilled 
water to remove the hydroxide, and preserved in 70% alcohol. All dis- 
sections were made under a binocular microscope in 70% alcohol in Syra- 
cuse watch-glasses. 


9] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 9 


ACKNOWLEDGMENTS 


This study was pursued under the supervision of Professor Alex. D. 
MacGillivray, to whom I am under the deepest obligations for all that his 
supervision has meant to me in the way of helpful suggestions and real 
inspiration. I must further thank him for permission to use his unpub- 
lished morphological nomenclature. I am also greatly indebted to Profes- 
sor S. A. Forbes for suggestions and for furnishing a large number of species 
from the collections of the Illinois State Natural History Survey and from 
the collections of the University of Illinois. I am further greatly indebted 
to Professor H. F. Wickham of the Iowa State University, who supplied 
me with a considerable number of species belonging to rare families; to 
Messrs. E. A. Schwarz and H. S. Barber, and the authorities of the United 
States National Museum for representatives of twelve very rare families 
from the collections of the Museum; to Mr. W. S. Blatchley of Indianapolis 
for many very rare species; to Dr. Edwin C. Van Dyke of the University 
of California for a specimen of a species of Othnius; and to Professor 
Henry C. Fall for a specimen of Hydroscapha. Of the many courtesies 
that Dr. Chas. P. Alexander of the Illinois State Natural History Survey 
has shown me I am duly appreciative. Finally, to Mrs. Elizabeth Stick- 
ney, who has helped me greatly in the preparation of the drawings, I am 
under deep obligations. 


10 ILLINOIS BIOLOGICAL MONOGRAPHS [10 


MATERIALS 


An effort has been made to make this study as comprehensive as pos- 
sible, including not only a wide series of families, but also a representation 
of the different subgroups within the families. Of the eighty-one families, 
exclusive of the Strepsiptera, listed by LeConte and Horn, representatives 
of all are embraced in this study. Leng in his recent catalogue lists one 
hundred and nine families. Of these one hundred and five have been stud- 
ied and figured, representing one hundred and forty-six species. The fami- 
lies in Leng’s catalog not included in this study are Telegeusidae with one 
species, Cerophytidae with two species, Murmidiidae with five species, 
and Monoedidae with one species. The fundamental structure of the 

ead is, except in a few cases, practically similar for the two sexes. The 
sex has, therefore, been disregarded, except in the case of the brenthid, 
Eupsalis minuta, the female of which has a long slender snout, as contrasted 
with the large broad snout of the male. The latter has been figured. 

A numberof attempts were made to arrange the figures in a linear 
series leading from the generalized to the specialized forms. All attempts 
proved unsatisfactory. No matter what structure or condition of a struc- 
ture was used, the structure showed itself to be unstable within narrow 
limits, and therefore could not be relied upon to illustrate a definite line 
of development. However, the meagre results obtained in trying to ar- 
range the drawings in a linear series emphasized an important fact: that 
the various families of Coleoptera and even the subgroups within the 
families, have developed along many lines. For this study, the arrange- 
ment finally decided on, including the species, is that adopted by Leng. 
This arrangement will be valuable, in so far as the head-capsule is con- 
cerned, in showing the need for further morphological work towards the 
improvement of our classification of the Coleoptera. Owing to the 
number of drawings presented in this study it was deemed more practical 
to omit detailed descriptions. The salient features, only, of the various 
structures are discussed. The following list is arranged according to 
Leng’s catalog, and includes only those species figured :— 


COLEOPTERA 


SUBORDER ADEPHAGA 
CARABOIDEA. 
1. Cicindelidae. 
Megacephalini.—Tetracha carolina (Figs. 2, 150, 297, 444). 
Cicindelini.—Cicindela formosa (Figs. 3, 151, 298, 445). 


11] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 11 


2. Carabidae. 
Carabinae.—Calosoma calidum (Figs. 4, 152, 299, 446). 
Harpalinae—Harpalus erraticus (Figs. 5, 23, 24, 153, 300, 447). 
. Amphizoidae——Amphizoa lecontei (Figs. 6, 154, 301, 448). 
. Omophronidae—Omophron americanum (Figs. 7, 155, 302, 449). 
. Haliplidae—Peltodytes 12-punctatus (Figs. 8, 156, 303, 450). 
6. Dytiscidae.—Cybister fimbriolatus (Figs. 9, 157, 304, 451). 
GYRINOIDEA. 
7. Gyrinidae.—Dineutes americanus (Figs. 10, 158, 305, 452). 


wn qe Go 


SUBORDER POLYPHAGA 


HYDROPHILOIDEA. 
8. Hydrophilidae. 
Hydraeninae.—Hydraena marginicollis (Figs. 11, 159, 306, 453). 
Hydroscaphinae.—Hydroscapha natans (Figs. 12, 160, 307, 454). 
Hydrophilinae——Hydrous triangularis (Figs. 13, 161, 308, 455). 
Hydrophilus obtusatus (Figs. 14, 162, 309, 456). 
SILPHOIDEA. 
9. Platypsyllidae—Platypsyllus castoris (Figs. 15, 163, 310, 457). 
10. Brathinidae——Brathinus nitidus (Figs. 16, 164, 311, 458). 
11. Leptinidae——Leptinus testaceus (Figs. 17, 165, 312, 459). 
12. Silphidae—Necrophorus carolinus (Figs. 18, 166, 313, 460). 
13. Clambidae—Clambus puberulus (Figs. 19, 167, 314, 461). 
14. Scydmaenidae.—Connophron fossiger (Figs. 20, 168, 315, 462). 
15. Orthoperidae.—Molamba lunata (Figs. 21, 169, 316). 
STAPHYLINOIDEA. 
16. Staphylinidae. 
Steninae.—Stenus flavicornis (Figs. 22, 170, 317, 463). 
Paederinae.—Gastrolobium bicolor (Figs. 25, 171, 318, 464). 
Staphylininae—Creophilus villosus (Figs. 26, 172, 319, 465). 
Tachyporinae.—Tachinus fimbriatus (Figs. 27, 173, 320, 466). 
Aleocharinae.—Aleochara lata (Figs. 28, 174, 321, 467). 
17. Pselaphidae.—Pilopius lacustris (Figs. 29, 175, 322, 468). 
18. Clavigeridae.—Fustiger fuchsi (Figs. 30, 176, 323). 
19. Ptilidae—Limulodes paradoxus (Figs. 31, 177, 324, 469). 
20. Sphaeriidae.—Sphaerius politus (Figs. 32, 178, 325, 470). 
21. Scaphidiidae —Scaphidium quadriguttatum (Figs. 33, 179, 326, 471). 
22. Sphaeritidae——Sphaerites glabratus (Figs. 34, 180, 327, 472). 
23. Histeridae.—Hister memnonius (Figs. 35, 181, 328, 473). 
CANTHAROIDEA. 
24. Lycidae.—Calopteron terminale (Figs. 36, 182, 329, 474). 
25. Lampyridae.——Photinus pyralis (Figs. 37, 183, 330, 475). 
26. Phengodidae.—Phengodes plumosa (Figs. 38, 184, 331, 476). 


12 ILLINOIS BIOLOGICAL MONOGRAPHS {12 


27. Cantharidae. 
Chauliognathini—Chauliognathus pennsylvanicus (Figs. 39, 185, 
186, 332, 477). 
Cantharini—Cantharis bilineatus (Fig. 187). 

28. Melyridae.—Collops nigriceps (Figs. 40, 188, 333, 478). 

29. Cleridae.—Trichodes nutalli (Figs. 41, 189, 334, 479). 

30. Corynetidae.—Necrobia rufipes (Figs. 42, 190, 335, 480). 
LYMEXYLOIDEA. 

31. Lymexylidae.—Hylecoetus lugubris (Figs. 43, 191, 336, 481). 

32. Micromalthidae.—Micromalthus debilis (Figs. 44, 192, 337). 
CUPESOIDEA. 

33. Cupesidae.—Cupes concolor (Figs. 45, 193, 338, 482). 
MoRDELLOIDEA. 

34. Cephaloidae.—Cephaloon lepturides (Figs. 46, 194, 339, 483). 

35. Oedemeridae.—Nacerda melanura (Figs. 47, 195, 340, 484). 

36. Mordellidae—Tomoxia bidentata (Figs. 48, 196, 341, 485). 

37. Rhipiphoridae.—Macrosiagon dimidiatum (Figs. 49, 197, 342, 486). 

38. Meloidae.—Epicauta marginata (Figs. 50, 198, 343, 487). 

39. Eurystethidae——Eurystethus debilis (Figs. 51, 199, 344, 488). 

40. Othniidae.—Othnius sp. (Figs. 52, 200, 345, 489). 

41. Pythidae——Pytho planus (Figs. 53, 201, 346, 490). 

42. Pyrochroidae.—Neopyrochroa flabellata (Figs. 54, 202, 347, 491). 

43. Pedilidae—Macratria murina (Figs. 55, 203, 348, 492). 

44, Anthicidae.—Notoxus anchora (Figs. 56, 204, 349, 493). 

45. Euglenidae.—Zonantes fasciatus (Figs. 57, 205, 350, 494). 


ELATEROIDEA. 

46. Cebrionidae.—Cebrio bicolor (Figs. 58, 206, 351, 495). 

47. Plastoceridae.—Euthysanius lautus (Figs. 59, 207, 352, 496). 

48. Rhipiceridae.—Sandalus niger (Figs. 60, 208, 353, 497). 

49. Elateridae.—Alaus oculatus (Figs. 61, 209, 354, 498). 

50. Eucnemidae.—Isorhipis ruficornis (Figs. 62, 210, 355, 499). 

51. Throscidae.—Throscus chevrolati (Figs. 63, 211, 356, 500). 

52. Buprestidae —Chalcophora virginiensis (Figs. 64, 212, 357, 501). 
DRYOPOIDEA. 

53. Psephenidae.—Psephenus lecontei (Figs. 65, 213, 358, 502). 

54. Dryopidae.—Helichus striatus (Figs. 66, 214, 359, 503). 

55. Elmidae.—Stenelmis sinuata (Figs. 67, 215, 360, 504). 

56. Heteroceridae.—Heterocerus undatus (Figs. 68, 216, 361, 505). 

57. Georyssidae.—Georyssus californicus (Figs. 69, 217, 362, 506). 
DASCILLOIDEA. 

58. Dascillidae——Eurypogon niger (Figs. 70, 218, 363, 507). 

59. Eucinetidae.—Eucinetus morio (Figs. 71, 219, 364, 508). 


13] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 13 


60. Cyphonidae.—Cyphon ruficollis (Figs. 72, 220, 365, 509). 
61. Chelonariidae.—Chelonarium errans (Figs. 73, 221, 366, 510). 
BYRRHOIDEA. 
62. Dermestidae.—Dermestes lardarius (Figs. 74, 222, 367, 511). 
63. Byrrhidae—Byrrhus americanus (Figs. 75, 223, 368, 512). 
64. Nosodendridae.—Nosodendron unicolor (Figs. 76, 224, 369, 513). 
RHYSODOIDEA. 
65. Rhysodidae.—Rhysodes americanus (Figs. 77, 225, 370, 514). 
» CUCUJOIDEA. 
66. Ostomidae.—Tenebroides sinuatus (Figs. 78, 226, 371, 515). 
67. Nitidulidae. 
Nitidulinae——Phenolia grossa (Figs. 79, 227, 372, 516). 
Cryptarchinae—Glischrochilus fasciatus (Figs. 80, 228, 373, 517). 
68. Rhizophagidae.—Rhizophagus bipunctatus (Figs. 81, 229, 374, 518). 
69. Monotomidae.——Phyconomus marinus (Figs. 82, 230, 375, 519). 
70. Cucujidae. 
Cucujini—Cucujus clavipes (Figs. 83, 231, 376, 520). 
Hemipeplini—Hemipeplus marginipennis (Figs. 84, 232, 377, 521). 
71. Erotylidae. 
Langurinae.—Languria mozardi (Figs. 85, 233, 378, 522). 
Erotylinae—Megalodacne fasciata (Figs. 86, 234, 379, 523). 
72. Derodontidae.—Derodontus maculatus (Figs. 87, 235, 380, 524). 
73. Cryptophagidae.—Anchicera ephippiata (Figs. 88, 236, 381, 525). 
74. Byturidae.—Byturus unicolor (Figs. 89, 237, 382, 526). 
75. Mycetophagidae——Mycetophagus punctatus (Figs. 90, 238, 383, 
527); 
76. Colydiidae. 
Bothriderini—Bothrideres geminatus (Figs. 91, 239, 384, 528). 
Cerylonini—Philothermus glabriculus (Figs. 92, 240, 385, 529). 
77. Lathrideridae —Melanophthalma cavicollis (Figs. 93, 241, 386, 530). 
78. Mycetaeidae—Phymaphora pulchella (Figs. 94, 242, 387, 531). 
79. Endomychidae.—Endomychus biguttatus (Figs. 95, 243, 388, 532). 
80. Phalacridae—Phalacrus politus (Figs. 96, 244, 389, 533). 
81. Coccinellidae——Hippodamia convergens (Figs. 97, 245, 390, 534). 
Adalia bipunctata (Figs. 98, 246, 391, 535). 
TENEBRIONOIDEA. 
82. Alliculidae.—Pseudocistela brevis (Figs. 99, 247, 392, 536). 
83. Tenebrionidae.—Alobates pennsylvanica (Figs. 100, 248, 393, 537). 
Tenebrio molitor (Figs. 101,.249, 394, 538). 
Boros unicolor (Figs. 102, 250, 395, 539). 
84. Lagriidae——Arthromacra aenea (Figs. 103, 251, 396, 540). 
85. Monommidae.—Hyporphagus sp. (Figs. 104, 252, 397, 541). 
86. Melandryidae.—Penthe obliquata (Figs. 105, 253, 398, 542). 


87. 
88. 
89. 
90. 
91. 
O27: 


ILLINOIS BIOLOGICAL MONOGRAPHS [14 


Ptinidae.—Ptinus brunneus (Figs. 106, 254, 399, 543). 
Anobiidae.—Sitodrepa panicea (Figs. 107, 255, 400, 544). 
Bostrichidae.—Bostrichus bicornis (Figs. 108, 256, 401, 545). 
Lyctidae.—Lyctus planicollis (Figs. 109, 257, 402, 546). 
Sphindidae.—Sphindus americanus (Figs. 110, 258, 403, 547). 
Cisidae.—Plesiocis cribrum (Figs. 111, 259, 404, 548). 


SCARABAEOIDEA. 
93. Scarabaeidae. 


Aphodiinae.—Aphodius fimetarius (Figs. 112, 260, 405, 549). 
Melolonthinae.—Dichelonyx elongata (Figs. 113, 261, 406, 550). 
Rutelinae.—Pelidnota punctata (Figs. 114, 262, 407, 551). 
Dynastinae.—Strategus julianus (Figs. 115, 263, 408, 552). 
Cetoniinae.—Osmoderma eremicola (Figs. 116, 264, 409, 553). 


94. Trogidae.—Trox suberosus (Figs. 117, 265, 410, 554). 

95. Lucanidae.—Pseudolucanus capreolus (Figs. 118, 266, 411, 555). 

96. Passalidae.—Passalus cornutus (Figs. 119, 267, 412, 413, 556). 
CERAMBYCOIDEA. 

97. Cerambycidae. 


Prioninae. 
Parandrini—Parandra brunnea (Figs. 120, 268, 414, 557). 
Prionini—Derobrachus brunneus (Figs. 121, 269, 415, 558). 
Cerambycinae. 
Spondylini—Spondylis buprestoides (Figs. 122, 270, 416, 559). 
Clytini—Glycobius speciosus (Figs. 123, 271, 417, 560). 
Lamiinae.—Tetraopes tetrophthalmus (Figs. 124, 272, 418, 561). 


98. Chrysomelidae. 


Donaciinae.—Donacia piscatrix (Figs. 125, 273, 419, 562). 
Orsodacninae.—Syneta ferruginea (Figs. 126, 274, 420, 563). 
Criocerinae.—Criocerus asparagi (Figs. 127, 275, 421, 564). 
Cryptocephalinae.—Cryptocephalus quadruplex (Figs. 128, 276, 
422, 565). | 
Eumolpinae.—Chrysochus auratus (Figs. 129, 277, 423, 566). 
Chrysomelinae.—Leptinotarsa decemlineata (Figs. 130, 278, 424, 
567). 
Galerucinae.—Diabrotica 12-punctata (Figs. 131, 279, 425, 568). 
Halticinae.—Blepharida rhois (Figs. 132, 280, 426, 569). 
Hispinae.—Anoplitis gracilis (Figs. 133, 281, 427, 570). 
Cassidinae.—Chelymorpha argus (Figs. 134, 282, 428, 571). 


99. Mylabridae.—Pachymerus gleditsiae (Figs. 135, 283, 429, 572). 
BRENTOIDEA. 

100. Brentidae.—Eupsalis minuta (Figs. 136, 284, 430, 573). 
CURCULIONOIDEA. 

101. Belidae.—Ithycerus noveboracensis (Figs. 137, 285, 431, 574). 


15] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 15 


102. Platystomidae——Eurymycter fasciatus (Figs. 138, 286, 432, 575). 
103. Curculionidae. 
Rhinomacerinae.—Rhinomacer pilosus (Figs. 139, 287, 433, 576). 
Rhynchitinae—Rhynchites bicolor (Figs. 140, 288, 434, 577). 
Attelabinae.—Attelabus analis (Figs. 141, 289, 435, 578). 
Otiorhynchinae.—Epicaerus imbricatus (Figs. 142, 290, 436, 579). 
Curculioninae.—Lixus fimbriolatus (Figs. 143, 291, 437, 580). 
Thecesterninae.—Thecesternus humeralis (Figs. 144, 292, 438, 
581). 
Calendrinae——Sphenophorus aequalis (Figs. 145, 293, 439, 582). 
SCOLYTOIDEA. 
104. Platypodidae.—Platypus flavicornis (Figs. 146, 294, 440, 583). 
105. Scolytidae. 
Scolytinae.—Scolytus quadrispinosus (Figs. 147, 295, 441, 584). 
Hylesininae——Dendroctonus valens (Figs. 148, 296, 442, 585). 


16 ILLINOIS BIOLOGICAL MONOGRAPHS [16 


HEAD-CAPSULE 


There exists a distinct homogeneity in the general character of the 
structure of the head-capsule of Coleoptera. Its uniform strong chitiniza- 
tion is typical. So is the spacious area occupied by the mouth-parts, 
producing a relatively broad cephalic end. Especially characteristic 
is the wide space between the occipital foramen and the submentum. 
Then, there is that indescribable similarity of structure, even between 
groups widely separated, that can best be appreciated from a thorough 
knowledge of the morphology. As an illustration, there is little super- 
ficial resemblance between Harpalus (Figs. 5 and 153) and Phalacrus 
(Figs. 96 and 244), either in external or in internal morphology. Their 
distinct differences are merely due to two divergent lines of development. 
The structures of the dorsal surface of Phalacrus have become highly 
specialized, whereas those of Harpalus are relatively generalized. On 
the other hand, on the ventral surface the metatentorina has remained 
in a relatively primitive condition in Phalacrus, whereas in Harpalus its 
position is highly specialized. The internal structures of Phalacrus are 
rudimentary or lacking, while in Harpalus they are in a well developed 
primitive state. Considering the degree of generalization of each species, 
there can hardly be any question that Harpalus is the more generalized.’ 
The above comparative description simply illustrates roughly the problems 
of complexity of development that are encountered. The two distinctive 
kinds of development as shown above for Harpalus and Phalacrus, that of 
specialization of the dorsal surface and that of separate specialization of 
the ventral surface, do not in the least necessarily parallel one another in 
the Coleoptera. Indeed, these two lines of development are predominantly 
divergent. In the majority of species, the development is trending towards 
the obliteration of sutures and consequent consolidation of sclerites, and 
towards the development of a compactness of form of the sclerites that do 
not consolidate. The general trend towards a cephalization of migratory 
structures is a part of this process, too, as well as the development of a 
stronger chitinization of the head-capsule asa whole. The entire phenome- 
non appears to be for purposes of strengthening the head. Besides 
Phalacrus typical examples are Tenebrioides (Fig. 78), Glischrochilus 
(Fig. 80), Megalodacne (Fig. 86), and all the Scarabaeoidea. On the 
other hand these processes have lagged behind on the ventral surface in 
Phalacrus and others. It is true that the hypothetical type (Fig. 149) 
shows a marked cephalization of the submentum, with obliteration of 


17} THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 17 


sutures resulting from this migration. Yet the predominant condition 
of the heads studied shows only a certain degree of removal from the 
primitive type. Stronger chitinization has probably kept pace with the 
cephalization of the dorsal surface, as well as the growing compactness 
of such a structure as the submentum. But the very significant structure 
of the ventral surface, the metatentorina, only shows a certain degree of 
removal from the primitive condition in most of the heads. 

Developmental processes such as are discussed above can be best 
worked out through a comparative study of a large series of forms. In 
fact the determination of the homologies of some structures entering into 
these developmental processes, as for example the various changes in 
the epicranial suture, and the determination of the nature and line of 
development of the area between the occipital foramen and the submentum, 
would probably be most difficult without this comparative study. The 
chief value of this study lies in all probability in the determination of 
homologies, to the end of understanding the lines of development present. 
The homology existing between the various structures of the head-capsule 
of Coleoptera and other orders of insects, particularly the generalized 
orders, seems to work out satisfactorily. From such an homology the 
hypothetical type was constructed without much difficulty. In general 
appearance the head is oblong and rather flattened dorso-ventrally. Such 
a form is fairly characteristic of generalized insects and of the more 
generalized Coleoptera. The mouth may be considered as directed 
cephalad. Such a direction is representative of the vast majority of 
the heads, and for purpose of convenience, at least, the following 
discussion considers the head as extending cephalad. Some possible 
exceptions in which the head appears to be directed ventrad are 
found in Calopteron (Fig. 329), Macrosiagon (Fig. 342), Isorhipis (Fig. 
355), Throscus (Fig. 356), Byrrhus (Fig. 368), and a few others. It 
should not be forgotten, however, that in primitive insects the mouth is 
directed ventrad, and the occipital foramen is on one side instead of at 
the opposite end. 

The line of closure of the head in the embryo is represented by the 
epicranial suture. The complete epicranial suture is typical of generalized 
insects. Where it is present in Coleoptera, this denotes a generalized 
condition. The primitive form of the epicranial suture is that of a deep 
inverted Y, with the cephalic ends of the arms near the lateral border of 
the labrum. The hypothetical head is represented as having a complete 
epicranial suture. The epicranial stem extends to a transverse line drawn 
through the middle of the compound eyes. Branching here the epicranial 
arms continue to the margin of the head cephalad of the compound eyes, 
A complete epicranial suture is not of general occurrence in the Coleoptera. 
It is practically complete in Hydrous (Fig. 13) and Hydrophilus (Fig. 14), 


18 ILLINOIS BIOLOGICAL MONOGRAPHS [18 


very distinct and sharply invaginated in both, particularly so in the former, 
and characteristic in form. Each arm reaches the margin of the head 
almost immediately cephalad of a compound eye, and the arms are not as 
generalized in position as they are in Epicauta (Fig. 50), where they are 
quite distinct. The only other occurrence of a complete epicranial suture 
is in Chelymorpha (Fig. 134). Here the arms meet the stem farther caudad 
than in the other genera named. The arms in this last genus are distinctly 
curved, as contrasted with the more or less straight arms in the above 
mentioned genera. 

The epicranial arms or some portion of them are present in all Coleop- 
tera, except possibly in Calopteron (Fig. 36) and Photinus (Fig. 37). 
One or more species of every superfamily of the Adephaga and Polyphaga, 
except the Elateroidea, Byrrhoidea, Rhysodoidea, and Rhynchophora, have 
the arms complete. In the Caraboidea they are prominent as nearly 
straight sutures across the head, as in Tetracha (Fig. 2), Cicindela (Fig. 3), 
Calosoma (Fig. 4), and Harpalus (Fig. 5). Their most generalized condi- 
tion in the Adephaga is found in OQmophron (Fig. 7) in which they extend 
from the meson at a sharp angle. Representative species of other super- 
families that have the arms complete are: Necrophorus (Fig. 18), Tachinus 
(Fig. 27), Chauliognathus (Fig. 39), Cupes (Fig. 45), Cephaloon (Fig. 46), 
Notoxus (Fig. 56), Heterocerus (Fig. 68), Eucinetus (Fig. 71), Myceto- 
phagus (Fig. 90), Tenebrio (Fig. 101), Bostrichus (Fig. 108), Aphodius 
(Fig. 112), and nearly all the Cerambycoidea. Species having parts of the 
epicranial stem preserved are not very common. In Omophron (Fig. 7), 
Tachinus (Fig. 27), Penthe (Fig. 105), and a number of the Cerambycoidea, 
parts of the cephalic end can be identified; in Omophron (Fig. 7), Phengodes 
(Fig. 38), Cupes (Fig. 45), Sitodrepa (Fig. 107), Blepharida (Fig. 132), 
and a number of the Rhynchophora, parts of the caudal end are present. 
Chalcophora (Fig. 64) and Tetraopes (Fig. 124) are peculiar in possessing 
practically all of the stem but little of the arms. The arms in Chalcophora 
are as short as in any other species studied. Parts of the arms are present 
in every degree of length from nearly meeting on the meson, as in Nosoden- 
dron (Fig. 76), to almost complete disappearance as in Chalcophora (Fig. 
357) and Rhysodes (Fig. 370). They also show varying degrees of dis- 
appearance and invagination, from the deep distinct invaginations of . 
such forms as Dineutes (Fig. 10), Necrophorus (Fig. 18), Tachinus (Fig. 
27), Heterocerus (Fig. 68), and Arthromacra (Fig. 103), to the faint or 
slender and shallow or not at all invaginated sutures characteristic of the 
Scarabaeoidea. 

The character of the invagination associated with the epicranial arms 
is not as simple as may be thought. In Harpalus (Figs. 5 and 24), the 
epicranial arms extend from the meson along the edge of the invagination 
to the pretentorinae, from which they extend to the bottom of the invagi- 


19] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 19 


nation, curve laterad, and continue to the margin of the head. The course 
of the epicranial arms can be better understood from Omophron (Fig. 7), 
a related genus, which has retained the cephalic portion of the epicranial 
stem. The line of the invagination appears to be and often is considered 
to be simply the clypeal suture. If a specimen of Harpalus is soaked for a 
long time in potassium hydroxide the invagination can be opened and the 
various structures in this region studied advantageously. The invagina- 
tion when opened (Fig. 24) will be seen to assume a deep wide wedge- 
shaped form, extending entirely across the dorsal surface of the head. The 
pretentorinae are located on the external dorsal surface just caudad of the 
cephalic margin of the invagination. Although the epicranial arms are not 
in evidence anywhere between the me: sn and the pretentorinae, it is 
assumed that the cephalic marginal ridge must represent them, since the 
pretentorinae are not only located caudad of the invagination, but the 
arms are quite distinct, extending from the pretentorinae to the bottom 
of the invagination, in which they then curve laterad and continue to the 
margin of the head. From a cross-section (Fig. 23) it will be seen that the 
pretentorium expands cephalad in characteristic form from the preten- 
torina along an epicranial arm to the bottom of the invagination. In 
Calosoma (Fig. 4) the same condition of this region is found as in Harpalus. 
In Omophron (Fig. 7) the epicranial arms are distinct between the preten- 
torinae, extending from the meson along the cephalic border of the invagi- 
nation. From Figure 24 it will be observed that the cephalic border of the 
invagination in Harpalus is along the imaginary line of the fronto-clypeal 
suture. This border may represent the cephalic limit of the front. The 
invagination, then, in Harpalus and Calosoma includes the entire front. 
The line of the invagination instead of being solely a part of the epicranial 
suture is in fact compound in nature, representing the approximation 
of the caudal borders of the front and postclypeus, and that part of it 
between the pretentorinae may be termed the “clypofrons.”’ Laterad of 
the pretentorinae to the margin of the head the line of the invagination is 
readily seen to be an approximation of a part of the vertex with the caudal 
border of the postclypeus and cannot be included in the clypofrons. 
Due to the more primitive position of the epicranial arms in Omophron 
the invagination in this genus contains only a part of the front, hence the 
line of the invagination between the pretentorinae is simple in nature. 
In Tachinus (Fig. 27) the epicranial stem extends distinctly into the in- 
vagination, the arms continuing in the same to the margin of the head. 
As should be expected, the pretentorinae are within the invagination. 
The line of the invagination in Tachinus is then of a different character 
from that of either Harpalus or Omophron. In Tachinus, it has nothing 
whatever to do with the epicranial suture nor with any other suture, being 
throughout the approximation of parts of the external dorsal surface of 


20 ILLINOIS BIOLOGICAL MONOGRAPHS (20 


the vertex and the front. It is obvious from the above discussion of three 
types of the invagination associated with the epicranial arms that the 
dorsal surface of the head-capsule in Coleoptera must be studied most 
carefully before a correct interpretation of the parts can be made. This 
is most true in the case of any invagination that may be present. The 
latter may not be readily observed when the head-wall is strongly and 
darkly chitinized, necessitating treatment of such specimens before the 
parts can be clearly made out. In Dermestes (Fig. 74), and perhaps others, 
all external trace of the line of the invagination may be lost. In such 
cases a true understanding of the parts can only be gained from an ex- 
amination of the ental surface of the head. But in specialized forms the 
ental indication of the invagination may also be effaced. 

The epicranial suture can always be located from the determination of 
the position of the pretentorina. The latter is always closely associated 
with the epicranial suture, being present either in or just off of the suture, 
in which case the pretentorina resembles a sort of pocket. There is 
usually little difficulty experienced in locating the suture. The cephalic 
ends of the arms are the most persistent parts of it, being present when 
the remainder of the suture cannot be identified. Interesting examples 
are found in most Rhynchophora, where the remnants of the epicranial 
arms are represented by short furrows located at the cephalic end of the 
snout. The epicranial arms are typically structures of the dorsal aspect, 
but with the shifting and modification of other parts of the head may be 
confined to the lateral aspect, as in Helichus (Fig. 359), Adalia (Fig. 391), 
or to the ventral aspect, as in Cybister (Fig. 157), Hydrous (Fig. 161) 
and Phalacrus (Fig. 244). From the preceding discussion of the epicranial 
suture it is seen that what appears superficially to be this suture may not 
be so. It is a difficult problem to understand the kind and amount of 
change that may have taken place. In a number of the Rhynchophora, 
for instance, what appears to be the epicranial stem (Figs. 146 and 147) 
may be only invaginations, for in these same species are lateral invagina- 
tions that are quite similar in form to the so-appearing epicranial stem. 
The epicranial stem seems to the writer to hold the strongest claims, so 
these invaginations are considered as such. So, in other instances, where 
a structure appears to be more definitely the epicranial suture than any- 
thing else, it is so interpreted. 

That part of the head-capsule not embraced by the three primary 
sclerites cephalad of the epicranial arms, the occiput, and the postgena, 
constitutes the vertex. Its extent is determined by the form and size 
of the three above mentioned areas. For instance, in those species with 
much reduced epicranial arms, as in Creophilus (Fig. 26), Adalia (Fig. 98), 
and Phalacrus (Fig. 96), the extent of the vertex is correspondingly in- 
creased. In the Rhynchophora, as represented by such species as Lixus 


21) THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 21 


(Fig. 143) and Sphenophorus (Fig. 145) it is very extensive, including 
practically all of the snout of the dorsal and lateral surfaces. The area 
on the lateral surfaces of the head, cephalad of the compound eyes, be- 
tween the latter and the epicranial suture, is the gena, a part of the vertex. 
The limits of the gena are not definite. The prominent ridge in many 
genera, dorso-mesad of each gena and antacoria, is the so called frontal 
ridge, that extends in the general direction from the epicranial arms to the 
mesal margin of the compound eyes. The frontal ridge is prominent in 
Harpalus (Fig. 5), Necrophorus (Fig. 18), Trichodes (Fig. 41), Neopyro- 
chroa (Fig. 54), Dermestes (Fig. 74), and many others. 

In generalized insects the occipital suture is confined to the ventral or 
caudal aspect, beginning near the lateral margin of the postcoila and 
extending around the caudal or dorsal margin of the occipital foramen. 
In the Coleoptera this suture arises laterad of the postcoila, extends 
cephalad for a considerable distance, then eurves abruptly laterad, ex- 
tending onto the dorsal aspect of the head, where it joins the suture of the 
other side of the meson. The genus Cicindela (Figs. 3, 151, and 298) 
possesses the most generalized condition of this suture found in the Coleop- 
tera. The cephalic end of the suture is modified into a ridge. This 
ridge is considered a later development, and is not shown in the hypothetical 
type. It unquestionably represents a part of the occipital suture, and can 
be identified in practically all the Coleoptera, as in such widely separated 
groups as Molamba (Fig. 168), Nacerda (Fig. 195) and Byturus (Fig. 237). 
The occipital suture separates the vertex from the occiput and the post- 
gena. Only the Caraboidea seem to possess with certainty an unmodified 
occipital suture. In Cicindela (Fig. 3) it is complete and nearly so in 
Tetracha (Figs. 2, 150, and 297), but very faint in great part. In Calo- 
soma (Fig. 152) the unmodified suture begins farther caudad and is more 
distinct. In Omophron (Fig. 302), two short, characteristically curved, 
lateral ridges no doubt represent remnants of the occipital suture. The 
ridge across the lateral aspect in Peltodytes (Fig. 303) may also represent 
this suture. In Cybister (Fig. 157) it is probably represented by the 
crescent-shaped suture on the ventral aspect. Ridges and furrows ap- 
pearing in the same general location in other species, such as Aleochara 
(Fig. 321), Throscus (Fig. 356), Cyphon (Fig. 365), and Aphodius (Fig. 
405), may possibly be homologized as occipital sutures. In most cases 
these ridges seem to be merely to mark the limits to which the head is 
telescoped in the prothorax. 

In those species possessing an occipital suture the occiput is recognized 
as a distinct area. It includes the region between the occipital foramen 
and the occipital suture as far as the postgena, appearing as a sort of broad 
band across the dorsal aspect, divided by the epicranial stem and in- 
distinguishably fused on the lateral aspect with the postgenae. Examples 


22 ILLINOIS BIOLOGICAL MONOGRAPHS [22 


of a well marked occiput are present in Tetracha (Fig. 2), Cicindela 
(Fig. 3), Calosoma (Fig. 4), and Harpalus (Fig. 5). In Omophron (Fig. 
302) the occipital suture is so short that the limits of the occiput cannot be 
definitely determined. In those species not possessing a recognizable 
unmodified portion of the occipital suture, the limits of the occiput can 
only be judged accordingly. Even in generalized insects the occiput is 
nearly always fused with the postgenae, and is so represented in the 
hypothetical type. 

There is a great similarity in the form and location of the compound 
eyes. The general form is oval. They are located near the middle of the 
lateral margin of the head. Such a form and location is given in the hypo- 
thetical type. There are a number of interesting variations in form from 
the normal type. Dineutes (Fig. 305) and Tetraopes (Fig. 124) have four 
complete eyes. This phenomenon is produced by a projection of a part 
of the vertex into the eye that in time completely separates the two halves. 
The line of closure between the projection and the opposite side is indicated 
by a distinct line—the exoculata. The beginning of such a projection 
is shown in Cephaloon (Fig. 46), Epicauta (Fig. 50) and many others. 
In Pseudocistela (Fig. 99) and Osmoderma (Fig. 116) the projection ex- 
tends more than half-way across the eye. In Throscus (Fig. 63) the 
projection nearly separates the two halves. The eyes of Peltodytes 
(Fig. 8), Photinus (Fig. 37) and Stenus (Fig. 22) are very large. Unusual 
forms of the eyes are found in Hypophagus (Fig. 104), where they are very 
long and narrow nearly meeting on the dorso-meson; in Cryptocephalus 
(Fig. 128), where they are prominent, crescent-shaped, and extend well 
caudad on the dorsal surface; and in Aphodius (Fig. 112), where they are 
relatively small and square-like. The eyes of Limulodes (Fig. 324) are 
transparent and almost invisible; those of Leptinus (Fig. 312) are com- 
pletely wanting. 

The oculata is present only on the inside periphery of the eye as a 
broad ring-like shelf. It is considered of little importance in this study. 
Its general size is indicated by the dotted area within the eyes of Cicindela 
(Fig. 298), Dineutes (Fig. 305), Passalus (Fig. 412), and a few others. 
In forms with divided eyes the two sides of an oculata are pressed together, 
forming an exoculata. 

The supratentorinae represent the point of attachment on the head- 
capsule of the supratentoria. They are not thought to be primary in- 
vaginations, and may probably represent no more than depressions. In 
the Coleoptera the supratentorinae are not prominent, as the pretentorinae 
and metatentorinae often are. They are situated on the dorsal surface of 
the vertex. Their presence is not general, occurring commonly only in the 
Staphylinoidea. Outside of this superfamily the supratentorinae are 
found only in Phyconomus (Fig. 82) and Philothermus (Fig. 92). The 


23] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 23 


supratentoria are usually attached to the inner membrane of the body-wall, 
but unless an actual mark of their presence is indicated on the external 
surface the supratentorinae are not considered as present. In generalized 
insects the latter are generally present. Their presence in the Coleoptera 
should indicate a primitive state. 

In all the Coleoptera examined, no indication of any ocelli has been 
observed. 

In generalized insects there is a ring-like sclerite surrounding the 
periphery of each antacoria. In Coleoptera this sclerite is present, but 
it is distinguished from the head-capsule by a ridge only. On most heads 
it is considerably reduced in size, about all that can be seen of it externally 
being its projection, the antacoila, upon which the scape of the antenna 
articulates. On the other hand, in Sandalus (Fig. 353), Derobrachus (Fig. 
120), Tetraopes (Fig. 124), Leptinotarsa (Fig. 130), and Anoplitis (Fig. 
133), the antennaria is quite prominent. The most generalized position 
of the antennaria is considered to be on the gena cephalad of the eye, 
notwithstanding that in generalized insects the antennariae are quite fre- 
quently found distinctly between the eyes. Embryology, however, 
shows that the antennae are postoral in origin. Furthermore, in coleop- 
terous larvae each antennaria is located cephalad of the ocellarae. Such 
a position in coleopterous adults should denote the more generalized condi- 
tion. The antennaria is very unstable in position. There is hardly a 
superfamily in which it does not appear in both the generalized position 
and elsewhere. In the Scarabaeoidea and Cerambycoidea, though the 
position of the antennaria varies within certain limits, yet it shows a char- 
acteristic location. In the former it is either on the lateral or ventral 
aspects, while in the latter it occurs only on the dorsal aspect. In no other 
large groups does the antennaria appear so constant in position. In 
Calopteron (Fig. 36) and Phengodes (Fig. 38) it is exceptionally large; in 
Dineutes (Fig. 305) and Alobates (Fig. 392) it is exceptionally small. 

The membrane attaching the antenna to the head-capsule is the 
antacoria. In removing the antennae the antacoria is torn, and as it plays 
no significant part in this study no attempt was made to represent it in 
every case. The antacoria varies in size depending upon the size and 
shape of the scape. It is indicated in a number of figures by the stippled 
area: Omophron (Fig. 7), Necrophorus (Fig. 313), Calopteron (Fig. 36), 
Phengodes (Fig. 38), and Chauliognathus (Fig. 332). 

The depression in the vertex, usually in the gena, within which the 
antennaria and antacoria are situated is the antacava. It is always pres- 
ent, so far as is known, and is developed into a deep socket in Dineutes 
(Fig. 305), Connophron (Fig. 315), Scolytus (Fig. 441), and Dendroctonus 
(Fig. 442). 

The points of invagination of the pretentoria on the head-capsule are 
the pretentorinae. They are always located along the epicranial suture 


24 ILLINOIS BIOLOGICAL MONOGRAPHS [24 


in the Coleoptera. In generalized insects and the more generalized 
Coleoptera, they are situated on the lateral margin of the head. They 
are, therefore, represented in this position on the hypothetical type. The 
pretentorinae have been identified in every species studied except possibly 
Calopteron (Fig. 36) and Photinus. In the latter they are represented by 
depressions caudad of the eyes. Their position along the epicranial suture 
varies greatly. In widely separated groups they may be primitively lo- 
cated, as illustrated in such diverse forms as Omophron (Fig. 7), Necroph- 
orus (Fig. 18), Scaphidium (Fig. 33), Chauliognathus (Fig. 39), Cepha- 
loon (Fig. 46), Nacerda (Fig. 47), Alaus (Fig. 61), Phyconomus (Fig. 82), 
and Glycobius (Fig. 123). The position of the pretentorina evidently 
cannot possess any important significance in every instance, yet its posi- 
tion may be characteristic sometimes. In the Scarabaeoidea it is never 
on the dorsal surface; in the Cerambycoidea it is always on the dorsal 
surface. In this respect, the pretentorinae and the antennariae behave 
similarly. As a matter of fact, they are usually associated together, but 
there are some striking exceptions. The antennariae of Macrosiagon 
(Fig. 49) are located well caudad of the cephalic margin of the eyes, while 
the pretentorinae are situated at the ventro-lateral margin of the head 
(Fig. 342). The opposite condition is found in Phenolia (Fig. 79). The 
antennariae in the vast majority of cases are caudad of the pretentorinae. 

The pretentorinae are the great landmarks of the head-capsule.. On 
their location the determination of the presence and position of the epi- 
cranial suture is often dependent, and, consequently, the homologies of 
large areas of the head-capsule. A case in point is that of the Rhyncho- 
phora, in which the pretentorinae are located near the cephalic end of the 
snout, on the dorso-lateral margin. The epicranial suture is reduced to 
the very short cephalic ends of the epicranial arms, and though we cannot, 
therefore, indicate with precision the cephalic limits of the vertex, its ap- 
proximate limits can be judged, which would show the vertex to occupy 
nearly all the dorsal and lateral aspects of the snout. 

The sclerite embraced by the epicranial arms is the front. In the 
hypothetical type (Fig. 1) its caudal and lateral limits are the epicranial 
arms. Its cephalic limit is indistinguishable, since the front is fused with 
the postclypeus. The approximate line of fusion is indicated by a dotted 
line. There is no external indication in any head of a fronto-clypeal suture. 
The size of the front depends upon the position and direction of the 
epicranial arms. In those species possessing the inverted Y type of arms, 
the front assumes considerable proportions, but where the arms have been 
forced into a more or less straight line across the head, the invagination 
associated with the epicranial arms includes practically the entire front. As 
mentioned previously, the epicranial arms extend in this manner across 
the head in a wide series of families. The front must hence assume this 


25) THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 25 


form. In just as wide a series of families, the epicranial arms are in 
process of disappearing. In such cases, the caudal limits of the front can 
only be judged approximately. In great reduction of the arms, as repre- 
sented by Phalacrus (Fig. 96) and Macrosiagon (Fig. 49), the vertex, 
the front and the postclypeus are indistinguishably fused into one area. 

In all species the clypeus is divided into two distinct sclerites, the 
postclypeus and the preclypeus. This condition is not present so far as I 
know in the more generalized insects such as the Orthoptera and Plecop- 
tera. In some Neuroptera, however, the preclypeus is a large character- 
istic sclerite, quite similar to what has been designated as the preclypeus 
in the Coleoptera. It may possibly represent the extraordinary develop- 
ment and differentiation of the labracoria, but its size, shape and form 
would militate against such an assumption. It seems much easier to 
believe that this area is a true sclerite, and in this discussion it will be so 
considered. 

The broad cephalic part of the area between the epicranial arms in the 
hypothetical type (Fig. 1) represents the postclypeus. In generalized 
Coleoptera it is of considerable size if the dorsal surface has retained a 
generalized form. The shape, form, and size of the postclypeus is cor- 
related with the position and extent of the epicranial arms, which has 
already been discussed. In highly specialized forms like the Scarabaeoidea 
(Figs. 114, 115, and 116), the postclypeus may be even more extensive. 
Among the Staphylinidae, the postclypeus may be very large in Tachinus 
(Fig. 27) and Aleochara (Fig. 28), and very small in Creophilus (Fig. 26). 
In Chalcophora (Fig. 357) the cephalic end of the vertex is located on the 
ventral aspect of the head, and the postclypeus is reduced to hardly more 
than a line. Among the Cerambycoidea the postclypeus is generally very 
large. In the Rhynchophora it is quite reduced in size. 

The caudo-lateral projection or lobe of the postclypeus is the clypealia. 
In Orthoptera and Plecoptera the clypealia is not separated from the re- 
mainder of the postclypeus. In the larvae of Corydalis it is a prominent 
distinct sclerite. The clypealia in the Coleoptera is often separated from 
the postclypeus proper by a distinct furrow or suture. It is quite loosely 
attached to the postclypeus in the Cicindelidae (Figs. 297 and 298), the 
Carabidae (Figs. 299 and 300), many of the Cerambycoidea (Figs. 419 and 
424), and others. Difficulty is often experienced in removing the mandi- 
bles from the head without detaching the clypealia. The close resemblance 
between the Neuroptera and the Coleoptera in other respects would lead 
one to believe that this similar structure in the two orders must be ho- 
mologous. The presence of this furrow in the Coleoptera is wide-spread, 
as a glance at the figures will show. It can probably show little signifi- 
cance as an indication of primitiveness. It must, though, have been 
present in the primitive Coleoptera, and is hence shown in the hypothetical 


type. 


26 ILLINOIS BIOLOGICAL MONOGRAPHS [26 


In most of the Orthoptera a small triangular area is present, extending 
from the precoila to the cephalic end of the occipital suture. This sclerite 
is known as the mandibularia. No such area has been located in the 
Coleoptera. 

The dorsal surface of the larvae of Corydalis is very generalized. On 
this surface there is a prominent submembranous sclerite between the 
postclypeus and the labrum, the preclypeus. Such a sclerite, very similar 
in size, form, texture, and position, is present in Tachinus (Fig. 27), 
Arthromacra (Fig. 103), Trichodes (Fig. 41), and Glycobius (Fig. 123). 
This sclerite is considered the preclypeus. Figure 23 is a longitudinal 
section of the dorsal aspect of the head of Harpalus, and shows the char- 
acteristic position of the preclypeus. It is always present in the Coleop- 
tera, though often considerably reduced in size. The preclypeus is al- 
ways membranous except in Photinus (Fig. 37), where it is chitinized 
and the labrum is membranous. Besides the forms mentioned above, 
the preclypeus is large and prominent in Necrophorus (Fig. 18), Conno- 
phron (Fig. 20), Macratria (Fig. 55), Philothermus (Fig. 92), Hippedamia 
(Fig. 97), and many others. Very frequently the cephalic end of the 
postclypeus is infolded, thus carrying the preclypeus and the labrum with 
it. In such cases the preclypeus cannot be seen from the dorsal aspect. 
The preclypeus, no matter how deeply it is infolded, is, except in a few 
cases, sharply differentiated from the postclypeus and the labrum. In 
Glischrochilus (Fig. 373) and Chauliognathus (Fig. 332) the postclypeus 
and the labrum were in such close approximation that the preclypeus could 
not be observed until the two above mentioned sclerites were separated, 
and this was possible only after long soaking in potassium hydroxide. 
In most of the Rhynchephora, due to the fusion or absence of the labrum, 
the preclypeus could not be identified. The preclypeus, however, was 
prominent in Attelabus (Fig. 141), and somewhat reduced in Epicaerus 
(Fig. 290). 

The broad prominent sclerite attached to the cephalic end of the 
clypeus in generalized insects is the labrum. In Coleoptera possessing 
other generalized structures, the labrum is typically of the same general 
form. The labrum is shown in the hypothetical type. In position the 
hypothetical labrum should be, with the preclypeus, in accordance with 
their condition in generalized insects, on the same general level with the 
remainder of the dorsal surface. The generalized form and position of 
the labrum is present in every superfamily except the Elateroidea, 
Dryopoidea, Rhysodoidea, Scarabaeoidea, and the Rhynchophora, in 
which the postclypeus has been infolded, thus forcing the labrum onto 
the ventral aspect. All the superfamilies containing species with the 
labrum generalized, contain about as many with it in various degrees of 
specialization, as to form, size, texture and position. The labrum in Con- 


27] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 27 


nophron (Fig. 20), Photinus (Fig. 37), Othnius (Fig. 52), Chelonarium 
(Fig. 73), Eurymycter (Fig. 138), and others, is large and membranous. 
The labrum of Aphodius (Fig. 260) is large but very thin and delicate. 
The labrum of Scolytus (Fig. 295) and Dendroctonus (Fig. 296) is prob- 
ably membranous. In the latter, a significant looking slightly chitinized 
structure is located in the membrane within the mouth that may represent 
thelabrum. In Thecesternus (Fig. 292) there isa membranous area closely 
joined to the postclypeus that probably represents the labrum. In 
Eupsalis (Fig. 284), Lixus (Fig. 291), Sphenophorus (Fig. 293), and 
Rhynchites (Fig. 288), there is an area within the mouth, bounded by 
furrows, that may be the labrum. Such are particularly suggestive in 
view of the fact that in the same location and lying flat against the post- 
clypeus a very thin but a relatively large and well chitinized labrum was 
found in Epicaerus (Fig. 290) and Attelabus (Fig. 289). The labrum in 
Isorhipis (Fig. 210), Nosodendron (Fig. 224), Phyconomus (Fig. 230), 
and Derobrachus (Fig. 269) is considerably reduced in size. It is present 
in every species, except possibly the rhynchophorous genera named 
above, where it is always said to be wanting. 

The prominent opening in the caudal part of the head is known as the 
occipital foramen. It is generally very large, but in some species, such as 
Connophron (Fig. 168), Cephaloon (Fig. 194), and Macratria (Fig. 203) 
is reduced in dimensions, due to the constriction of the caudal end of the 
head. In Calopteron (Fig. 182), Photinus (Fig. 183), Alaus (Fig. 209), 
and Tetraopes (Fig. 272), the occipital foramen is extraordinarily large. 

In order to understand clearly the developmental processes that take 
place on the ventral surface, it is necessary to consider a sclerite, belonging 
to the mouth-parts, the submentum. Im generalized insects the sub- 
mentum is not only adjacent to but is one of the covering parts of the 
occipital foramen. Such a position is not found in the Coleoptera. Here, 
it is always located cephalad of the occipital foramen, with a distinct area 
between the two. In the vast majority of heads this area is very wide. 
It is considered as having been present in primitive forms, and is shown on 
the hypothetical type. The submentum in generalized insects is a large 
quadrangular movable plate. Many genera of Coleoptera show a similar 
size, form, and mobility, as in Leptinus (Fig. 165), Necrophorus (Fig. 166), 
Stenus (Fig. 170), Nacerda (Fig. 195), Neopyrochroa (Fig. 202), Alaus 
(Fig. 209), Heterocerus (Fig. 216), Cyphon (Fig. 220) and Byrrhus (Fig. 
223). In these three characters, and the additional one of position in re- 
spect to the paracoila, which in generalized insects is normally found 
beneath the submentum, that of the Adephaga seems to be the most primi- 
tive. The innumerable sizes and forms assumed by this structure through- 
out the entire series of families can best be judged by glancing at the figures. 
It is extraordinarily large in Rhysodes (Fig. 225). 


28 ILLINOIS BIOLOGICAL MONOGRAPHS [28 


The invaginations on the external surface of the head-capsule of the 
metatentoria are the metatentorinae. In the Orthoptera the meta- 
tentorinae are located along the cephalo-lateral or ventro-lateral border 
of the occipital foramen as invaginations between the maxillariae and the 
postgenae. They are not in any way associated with the submentum in 
generalized insects or in the Coleoptera. The same relative position of 
the metatentorinae is maintained in the Plecoptera. In a number of 
Coleoptera, as in Helichus (Fig. 214), Stenelmis (Fig. 215), Heterocerus 
(Fig. 216), and even in-the platystomid, Eurymycter (Fig. 286), this same 
generalized position of the metatentorinae is found. In a number. of 
Coleoptera the metatentorinae are situated considerably cephalad of 
the occipital foramen. The question might be raised as to whether the 
metatentorinae that are so located could possibly be more generalized in 
position than those situated adjacent to the occipital foramen? In 
every instance in which the metatentorinae are located cephalad of the 
occipital foramen, a suture connects the metatentorinae with the occipital 
foramen. In only a few cases does the suture extend much farther 
cephalad than the metatentorinae. This suture in the vast majority of 
heads studied does not extend cephalad. It is readily seen how the meta- 
tentorinae might be drawn cephalad and as a result a suture be formed 
marking their line of migration. In such a process one would naturally 
not expect to find a suture located cephalad of the metatentorinae, and 
in the cases in which the suture does extend so it is easy to understand 
that the force of the cephalic pull might have been communicated to this 
region, producing in consequence a suture or invagination. Due to the shape 
of the head, it is most difficult to believe that the metatentorinae could be 
drawn caudad, and if they were so drawn, it would seem that in this process 
there would be formed a suture cephalad of the metatentorinae, marking 
the line of migration. In this discussion the generalized position of the 
metatentorinae will be considered as that of its generalized position in more 
primitive insects, at or near the occipital foramen. 

In the development of the coleopterous head the metatentorinae have 
shown a tendency to migrate cephalad. The cephalic migration of the 
metatentorinae and the ventral migration of the pretentorinae and other 
structures, were no doubt due to the same force, the result being a closer 
approximation of parts, which naturally supplied increased firmness to the 
head’s mechanics of operation. The Dryopoidea show the most general- 
ized position of the metatentorinae. Genera of this superfamily have been 
mentioned above. The Elateroidea probably possess the next most gen- 
eralized metatentorinae, such as in Sandalus (Fig. 208) and Alaus (Fig. 
209). The Cucujoidea show the metatentorinae just a little removed 
from the occipital foramen, as in Megalodacne (Fig. 234), Anchicera (Fig. 
236), Philothermus (Fig. 240), and others. In the genera of other super- 


29} THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 29 


families, as Nosodendron (Fig. 224), Anoplitis (Fig. 236) and Tetraopes 
(Fig. 272), almost the same degree of primitiveness is shown. The large 
superfamily Mordelloidea show the metatentorinae to have migrated to 
about half the distance between the occipital foramen and the submentum. 
This condition is fairly consistent throughout the group. In the Bostri- 
choidea, the Scarabaeoidea, and the Cerambycoidea, the metatentorinae 
show considerable variation in position. This is shown by a comparison of 
their position in Bostrichus (Fig. 256) and Sphindus (Fig. 258). In the 
families to which Tetracha (Fig. 150), Calosoma (Fig. 152), Cybister 
(Fig. 157), Dineutes (Fig. 158), Necrophorus (Fig. 166), and Glycobius 
(Fig. 271) belong, the metatentorinae have advanced very far cephalad, 
near to the submentum. In Photinus (Fig. 183) and Chauliognathus 
(Fig. 185) they are located on or quite near the paracoila. 

There is a narrow plate surrounding the lateral and caudal margins 
of the occipital foramen in some generalized insects, between which and the 
postgenae the metatentorinae are invaginated. This plate has disappeared 
in the Coleoptera. 

The structure connecting the head-capsule with the prothorax is 
called the cervix. It is normally composed of membrane, and a number 
of cervical sclerites. The size of the cervix depends upon the size of the 
occipital foramen, and the degree of mobility of the head. In the Lampy- 
roidea and some other forms the cervix is very large. The cervix in 
Rhysodes is composed of tough fibrous membrane, quite different in 
structure from the normal cervix. In nearly all of the Rhynchophora the 
cervix is heavily supported by strong tendons attached at its cephalic 
end. These tendons take care of the added strain on the cervix due to 
the elongation of the snout. There are more or less small cervical tendons 
appearing occasionally throughout the whole series of families studied. 
In Molamba (Fig. 21) the cervix is invaginated within the prothorax, 
doubling upon itself. The cervix in Bostrichus (Figs. 256 and 401) 
doubles back upon the head-capsule, which is produced into a round 
projection. 

The most prominent and persistent cervical sclerites are the pleural 
cervical sclerites, the cervepisternum and the cervepimeron. The former 
is usually the larger of the two, and articulates at its cephalic end either 
against an odontoidea or simply against the undifferentiated area sur- 
rounded by the occipital foramen. The latter usually extends in a different 
direction from the former, and articulates at its cephalic end with the cerve- 
pisternum and at its caudal end with the prothorax. In Cantharis (Fig. 
187), Macratria (Fig. 348), Psephenus (Fig.358) and others, there is a single 
large sclerite present. In the Adephaga, in Leptinus (Fig. 312), Hypor- 
phagus (Fig. 397), Pseudocistela (Fig. 392), and many others, there is a 
single small subcircular sclerite present. Both of these types probably 


30 ILLINOIS BIOLOGICAL MONOGRAPHS [30 


represent the cervepisternum. Ina very large number of genera cervical 
sclerites are always wanting. They are poorly or not at all developed in 
the Cerambycoidea. None of the Rhynchophora studied possess a 
cervical sclerite except Eurymycter (Fig. 432), in which it is very small. 
The ventral cervical sclerite is the cervisternum. Hister (Fig. 181), 
Nacerda (Fig. 195), Cucujus (Fig. 231), and a few others, possess two small 
cervisterna, while Tomoxia (Fig. 196) possesses a long narrow one. The 
cervisternum is on the whole of infrequent occurrence. The dorsal 
cervical sclerite is called the cervinotum. It occurs even less frequently 
than the cervisternum. Hydrous (Fig. 13) possesses a subquadrangular 
distinctly chitinized cervinotum. In Aleochara (Fig. 28) the cervinotum 
is divided into two distinct lightly chitinized subtriangular sclerites. 
Two much larger square-like sclerites are situated caudad of these. All 
of the Hydrophilidae and Scarabaeidae possess setaceous caudo-lateral 
sclerites, which do not seem to be present in the other genera studied. 

Owing to the strong chitinization of the head and the close fit of the 
head in the prothorax, there is little need for a special process or projec- 
tion on the head for the articulation of the cervepisternum. Such a process 
is called an odontoidea. Some of the species in which it does occur are 
Scaphidium (Fig. 179), Encinetus (Fig. 219), Cyphon (Fig. 220), Byrrhus 
(Fig. 223), Nosodendron (Fig. 224), and Arthromacra (Fig. 251). The 
latter genus, it is interesting to note, possesses no cervepisternum. 

That part of the head-capsule on the caudal surface, mesad of the oc- 
cipital suture and ventrad of each occiput, in generalized orthopterous 
insects is a postgena. The occiput is considered as extending to near the 
middle of the dorso-ventral length of the occipital foramen, thus limiting 
the dorsal extent of the postgenae. The latter are widely separated from 
each other by the occipital foramen. The lateral parts of the large sub- 
mentum distinctly cover the mesal parts of the postgenae. In the Coleop- 
tera the occipital suture separates this region from the remainder of the 
head-capsule, as in generalized insects, and the occiput is also indis- 
tinguishably fused with the postgenae. But the postgenae, instead of 
being widely separated and their mesal parts being covered by the lateral 
parts of the submentum are directly connected by the broad area located 
between the occipital foramen and the submentum (Fig. 149); and the sub- 
mentum is attached to the mesal portion of the cephalic margin of the 
postgenae. This area is indistinguishably fused with and undifferentiated 
from the postgenae in the hypothetical and the more generalized types of 
ventral surface. 

In generalized insects the submentum is joined to the cervix by the 
undifferentiated part of the cervix, the cervacoria. In the cephalic migra- 
tion of the submentum, a part or all of the cervacoria must have been 
drawn in behind. The postgenae alone bordered the lateral margins of 


31] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 31 


the submentum and the cervacoria. A possible line of development may 
have been the chitinization of the cervacoria and the disappearance of the 
sutures separating it from the postgenae. The broad area between the 
occipital foramen and the submentum would in such a case be a modifica- 
tion of part or all of the cervacoria. It is much easier to believe, instead, 
that because of the membranous condition of the cervacoria, no strong 
resistance was offered to an approach of the mesal margins of the chitinous 
postgenae, which would migrate thus to serve as a firm foundational 
support for the submentum, as well as to strengthen the solidity of the 
head-capsule, as a whole. The mesal margins would in time approach 
so close as to press the two sides of the cervacoria into a line. Fusion of the 
mesal margins of the postgenae would finally take place, and the cervacoria 
would be divided into two parts. One part would be attached to the sub- 
mentum entirely separated from that portion of the cervacoria bordering 
the occipital foramen, and would be finally reduced to a suture. The 
other part of the cervacoria would remain as a portion of the cervix. 
Whether the mesal margins of the postgenae would approach the meson 
as broad surfaces, or as narrow ones and later elongate, it would be dif- 
ficult to state with certainty, though the latter would probably happen. 
In the primitive coleopterous head it is not unlikely that the head was 
much shorter, and that the area between the occipital foramen and the 
submentum was correspondingly shorter, so that there would not be the 
necessity for a broad fusion of the mesa] margin of the postgenae. So 
far as observed there has been retained in no coleopterous head any 
marks of the line of fusion of the postgenae. 

Abundant evidence is found for the conclusion that the broad area 
between the occipital foramen and the submentum must be a part of the 
postgenae. A similar condition as in the Coleoptera is present in many 
families of insects. In many Hymenoptera the mesal margins of the post- 
genae are fused between the occipital foramen and the articulation of the 
labium. That this is the true interpretation of this structure is shown by 
the fact that there is often a suture on the meson showing the line of fusion; 
and is further substantiated by the fact that this area bears on its ventral 
margin the paracoilae. In all cyclorrhaphous and orthorrhaphous Diptera 
the area ventrad of the occipital foramen is a continuous chitinized piece, 
similar to that found in the Coleoptera, and is derived from the fusion of 
the mesal margins of the postgenae. 

It may be well to add here that the expression ‘“‘cephalic migration,”’ 
as applied to the changed location of such a structure as the submentum, 
may be only relatively correct in its suggestion. Very probably the oc- 
cipital foramen in Coleoptera has migrated dorsad, at least it has assumed 
this typical position. Such a migration in itself would produce an elonga- 
tion of the ventral surface, with a consequent production of the broad area 


32 ILLINOIS BIOLOGICAL MONOGRAPHS {32 


between the occipital foramen and the submentum. Whether the force 
exerted on the head was directed more towards the cephalization of the 
submentum or towards the dorsalization of the occipital foramen it would 
be hard to say. The condition resulting would be in either case approxi- 
mately thesame. For purposes of convenience and simplicity of language, 
the expression “‘cephalic migration” is used in this discussion. 

This broad area between the occipital foramen and the submentum 
is sometimes designated as the gula. Usually, though, the term gula is 
used to indicate a sclerite, on the meson of the ventral aspect, separated 
from the remainder of the head-capsule by distinct subparallel sutures, 
the gular sutures. The term gula cannot satisfactorily be applied to both 
an indefinite region and a distinct sclerite. The gula is considered in the 
latter sense in this discussion. For the present the area between the oc- 
cipital foramen and the submentum will simply be designated as the mesal 
parts of the postgenae. 

The cephalic end of a postgena is usually modified into a rather flat 
area sloping towards the meson, upon which is situated a paracoila and a 
postcoila. This flat area is distinguished from the remainder of the post- 
gena by a distinct ridge, which usually extends in a deep curve from near 
the lateral margin of a postcoila to near the caudo-lateral margin of the 
submentum. Sometimes this ridge is directed towards the occipital fora- 
men, as in Leptinus (Fig. 165), Cantharis (Fig. 187), Macrosiagon (Fig. 
197), Isorhipis (Fig. 210), Psephenus (Fig. 213), Helichus (Fig. 214), and 
others. Attention has already been called to the fact that the cephalic 
portion of this ridge represents the cephalic end of the occipital suture. 
This modified part is reduced in size or indistinguishably fused with the 
remainder of the head, in Photinus (Fig. 183), Eucinetus (Fig. 219), 
Alobates (Fig. 248), Tenebrio (Fig. 249), Hyporphagus (Fig. 252), most of 
the Scarabaeoidea, Sphenophorus (Fig. 293), Eupsalis (Fig. 284), and 
Lixus (Fig. 291). 

There seems to be considerable confusion as to what constitutes the 
gula. Some investigators consider it as simply the central portion of the 
ventral surface of the head-capsule. Others restrict it to the distinct 
sclerite appearing on the meson of the ventral surface of certain insects, 
including the Coleoptera. Since this sclerite is distinctive and character- 
istic it needs a name. The term gula is quite satisfactory to apply to it. 
The origin of the gula also rests in considerable confusion. Comstock and 
Kochi (1902) consider it the sternum of the cervical segment, and to 
strengthen their argument they cite the situation in Corydalis, in which 
they state that the sternellum of the cervical segment is retained back of 
the gula, and they figure it as the small quadrangular sclerite immediately 
caudad of the gula. They do not mention the very much larger rectangular 
cervical sclerite caudad of their “‘sternellum.”’ The larger sclerite is sug- 


33] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 33 


gestive of the sternellum, and the smaller one would then represent their 
“sternum.”’ It is generally stated that the gula is derived from the chitini- 
zation of the neck membrane or cervix. In the discussion preceding, 
dealing with the metatentorinae and the postgenae, I have attempted to 
show the impossibility of such a derivation. In many orders of insects 
structures on the caudal aspect of the head have been designated as the 
gula. My interpretation would prevent the recognition of the presence 
of the gula in any insects other than the Coleoptera, Neuroptera, and 
Trichoptera. 

In some Coleoptera there is no gula (Figs. 168, 177, and possibly 286), 
whereas in others there is a complete gula (Figs. 150, 157, 172, 185, 267, 
and 296). Between these extreme types there are found in the Coleop- 
tera all gradations of a gula in process of formation (Figs. 156, 187, 210, 
245, and 257). Such a range of variation in a structure simply emphasizes 
the importance of a comparative study of a large series of forms. The 
question as to which is the more generalized condition, the presence of a 
complete gula or the absence of one, has been previously discussed, with 
the verdict in favor of the latter condition. It would then be impossible, 
other reasons not being considered, for the gula to be the sternum of the 
cervical segment. The gula is the sclerite formed by the migration of the 
metatentorinae from the occipital foramen towards the submentum, and 
must be derived from the postgenae. In this migration of the metaten- 
torinae sutures are produced which are known as the gular sutures. The 
area between the gular sutures is the gula. It is evident, then, that the 
presence and extent of the gula depend upon the position of the metaten- 
torinae and the sutures which they produce. The gula is complete in all 
the Adephaga except Peltodytes (Fig. 156), in the Silphidae, the Staphy- 
linidae, the Sphaeriidae, the first four families of the Canthroidea, and the 
Scarabaeidae except Pseudolucanus (Fig. 266). Isolated examples in 
other families of a complete gula are Scaphidium (Fig. 179), Helichus 
(Fig. 214), Cyphon (Fig. 220), Byrrhus (Fig. 223), and Leptinotarsa 
(Fig. 278). The gular sutures nearly meet in Gastrolobium (Fig. 171) 
and Creophilus (Fig. 172), and are entirely confluent in Necrophorus 
(Fig. 166), Scaphidium (Fig. 179), Hister (Fig. 181), Phengodes (Fig. 184), 
Chauliognathus (Fig. 185), and in all the Rhynchophora except Eurymycter 
(Fig. 286) and Rhinomacer (Fig. 287) in which genera the gular sutures 
are very widely separated. In Rhinomacer the gular sutures extend nearly 
half the distance to the submentum. The gula in cases of confluency of 
the middle portion of the gular sutures on the meson is simply invaginated. 
The gula is complete but extremely short in Calopteron (Fig. 182) and 
Photinus (Fig. 183). The-cephalic ends of the gular sutures meet on the 
meson near the occipital foramen in Philothermus (Fig. 240) and Anoplitis 
(Fig. 280). The gula is partially membranous in Nosodendron (Fig. 224), 


34 ILLINOIS BIOLOGICAL MONOGRAPHS [34 


Sitodrepa (Fig. 255), and Plesiocis (Fig. 259). Part of it is deeply in- 
vaginated transversely in Scaphidium (Fig. 179), Chauliognathus (Fig. 
185), Helichus (Fig. 214), Stenelmis (Fig. 215), and others. 

Most of the sclerites of the head-capsule are so closely united in some 
Coleoptera as to appear as a single piece. Strauss-Durckheim (1828) so 
regarded this region in the head-capsule of the May-beetle, and named it 
the epicranium. Used in the sense of indicating a closely united area, 
the term seems satisfactory and may often prove convenient. It can then 
be only a relative term, including at times no more than the paired sclerites 
of the head, when the epicranial suture is well developed. Occasionally, 
the preclypeus and the labrum are closely joined to the head-capsule. 
In such cases, the epicranium would embrace these structures, also. 

The small rather concave projections at the caudo-mesal margins of 
the postgenae against which the maxillae articulate are the paracoilae. 
They are usually easily identified, as in Molamba (Fig. 169), Pytho (Fig. 
201), Heterocerus (Fig. 216), and Phymaphora (Fig. 242). They are 
usually chitinized, but are membranous in a considerable number of genera. 
The paracoilae are insignificant in size in Gastrolobium (Fig. 171), all of 
the Elateroidea, Pseudocistela (Fig. 247), and Tenebrio (Fig. 249). In 
generalized insects the paracoilae are situated beneath the submentum. 
They are found in a similar position in the Adephaga (Figs. 150, 152, 154, 
157, and 158), in Hydrous (Fig. 161), and a few others. They are also 
always located on the postgenae in generalized insects. This position is 
of great importance in determining the identity of the postgenae in special- 
ized insects. 

At the cephalic end of a postgena is always found a distinct crescent- 
shaped acetabulum—the postcoila, against which the postartis of the 
mandible articulates. Throughout the genera the postcoilae exhibit 
some degree of difference in exact position upon the postgenae, in size, 
and in degree of shallowness. Their form and position are indicated in 
Calosoma (Fig. 152), Sphaerius (Fig. 178), Notoxus (Fig. 204), and Dero- 
brachus (Fig. 269). In generalized insects the postcoilae are also always 
located on the postgenae, and their position is of equal importance with 
that of the paracoilae in determining the identity of the postgenae. 

The rounded condyle on the ventral surface of each clypealia, against 
which the preartis of the mandible articulates is the precoila. It is usually 
crescent-shaped, but sometimes, as in Peltodytes (Fig. 156), Cybister 
(Fig. 157), Creophilus (Fig. 172), Endomychus (Fig. 243), Dichelonyx 
(Fig. 261), and others, the form is spherical. The precoilae are large in 
Macrosiagon (Fig. 197), Epicauta (Fig. 198), Isorhipis (Fig. 210), Chauliog- 
nathus (Fig. 185), Bostrichus (Fig. 256), and others, and small in Dineutes 
(Fig. 158), Photinus (Fig. 183), Helichus (Fig. 214), Derodontus (Fig. 
235), and particularly so in Psephenus (Fig. 213). The precoilae can 


35] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 35 


readily be recognized by their characteristic form. Since they are always 
located on the caudo-lateral lobe of the postclypeus, or the clypealia of 
certain insects, they are a great aid in determining the limits of the post- 
clypeus. 

The endoskeleton of the head is known as the tentorium. It is com- 
posed of two anterior and two posterior areas or projections, and their 
various modifications. The anterior arms arise from the pretentorinae, 
and are known as the pretentoria. The posterior arms arise from the 
metatentorinae, and are known as the metatentoria. In generalized in- 
sects one end of the pretentorium expands along and is continuous with the 
epicranial suture. Each extends in a caudo-mesal direction, and narrows 
for a short distance, then expands along its mesal margin until a fusion 
is formed with the pretentorium of the other side, producing the cephalic 
bridge, or laminatentorium. The pretentoria separate and then fuse 
again farther caudad with each metatentorium. The metatentoria ex- 
tend cephalo-mesad a very short distance, their mesal margins expand 
and completely fuse on the meson, producing the caudal bridge or corpo- 
tentorium. The fusion of the pretentoria and the metatentoria is sup- 
posed to take place along the cephalic margin of the corpotentorium. 
The dorsal projections arising from the lateral margins of the pretentoria 
and extending toward and attached to the dorsal wall of the head, are 
the supratentoria. The ring-like plate surrounding the inside periphery 
of the occipital foramen is indistinguishably fused with and is a part of the 
metatentoria. The tentoria, as a whole, are distinctly chitinized and well 
developed. The typical condition of the tentorium in generalized insects 
is practically duplicated among the Coleoptera. The hypothetical type 
(Fig. 443) has been constructed with this similarity in mind. The greatest 
difficulty experienced was in deciding upon the primitive type of lamina- 
tentorium, whether it should be represented as complete or incomplete, 
that is, whether the two sides of the laminatentorium fuse on the meson 
or not. Many Coleoptera that in other respects are quite generalized do 
not show a complete laminatentorium, as Tetracha (Fig. 444), Omophron 
(Fig. 449), Dineutes (Fig. 452), Leptinus (Fig. 459), Tachinus (Fig. 460), 
and Stenelmis (Fig. 504). The hypothetical laminatentorium is repre- 
sented as nearly meeting on the meson. At least, such a condition is 
thought to be not far removed from that which actually existed in the 
primitive Coleoptera. Limulodes (Fig. 469), Eurystethus (Fig. 488), 
Pytho (Fig. 490), Philothermus (Fig. 529), Melanophthalmus (Fig. 530), 
Hyporphagus (Fig. 541), Sphindus (Fig. 547), and others, possess practi- 
cally no trace of a laminatentorium, but well developed supratentoria. The 
atter are fairly well developed in Photinus (Fig. 475), Collops (Fig. 478), 
and Alaus (Fig. 498), but there is neither a laminatentorium nor a corpo- 
entorium present. There is no trace of any one of the three above 


36 ILLINOIS BIOLOGICAL MONOGRAPHS (36 


mentioned structures in Isorhipis (Fig. 499) and Throscus (Fig. 500). Phal- 
acrus (Fig. 533) and Eurymycter (Fig. 575) possess only the rudiments of 
the pretentoria and metatentoria. The tentoria of the Cerambycoidea 
(Figs. 557, 560 and 566) are very delicate and membranous. The preten- 
toria, the metatentoria, and the corpotentorium are always complete, while 
the laminatentorium.and supratentoria are always either rudimentary or 
absent except in Pachymerus (Fig. 572) in which the supretentoria are 
present. Other genera showing completely membranous tentoria are 
numerous. Among these are Cupes (Fig. 482), Eurystethus (Fig. 488), 
Rhysodes (Fig. 514), Languria (Fig. 522), and Pseudocistela (Fig. 536). 
A generalized condition of the pretentorium, characterized by a strong 
chitinization as a whole, and possessing a broad flaring cephalic end, is 
found in the Adephaga (Figs. 449 and 451), Leptinus (Fig. 459), Necro- 
phorus (Fig. 460), the Staphylinidae (Figs. 465 and 467), Georyssus (Fig. 
506), Eucinetus (Fig. 508), Dermestes (Fig. 511), and Derodontus (Fig. 
524). There are all degrees of gradation present from the most generalized 
pretentoria to those very delicate membranous ones represented by such 
forms as Heterocerus (Fig. 505), Endomychus (Fig. 532), Pseudocistela 
(Fig. 536), Hyporphagus (Fig. 541), the majority of the Cerambycoidea, 
and the Rhynchophora. A very prevalent type, possessing a distinctly 
chitinized cephalic end and a membranous caudal portion sharply sepa- 
rated from the former, is represented in Epicauta (Fig. 487), Pytho (Fig. 
490), Chalcophora (Fig. 501), Alobates (Fig. 536), Bostrichus (Fig. 545), 
Diabrotica (Fig. 568), Dendroctonus (Fig. 585) and most of the Scara- 
baeoidea. Rudimentary pretentoria are found in a number of genera, as 
Calopteron (Fig. 474), Tenebroides (Fig. 515), Phalacrus (Fig. 533), 
and perhaps all of the Rhynchophora, except Dendroctonus. The pre- 
tentoria of the Rhynchophora are for the most part very delicate and 
fragile. The difficulty of making a dissection showing the pretentoria 
intact is intensified by the close packing within the snout of the greatly 
developed tendons of the mouth-parts and the strongly chitinized pharynx. 
In no instance, except in Dendroctonus was a pretentorium preserved 
intact. In Scolytus (Fig. 584), the pretentorium is evidently rudimentary, 
but in none of the other genera is there a clear indication of such being the 
case, owing to the presence of frayed ends, suggesting that not all of the 
pretentorium has been seen. The presence in the Rhynchophora (Figs. 
433, 435, 437, 439 and 441) of a suture in the right position for an epi- 
cranial suture, an invagination within the suture that suggests the preten- 
torina, and a projection arising from the invagination, all furnish evidence 
that this projection is probably the cephalic portion of the pretentorium. 
The pretentorium of Passalus (Fig. 413) is extraordinarily developed. 
The cephalic part extends as a slender bar dorso-caudad, nearly half way 
to the occipital foramen, then bends suddenly and extends as a huge 


37] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 37 


straight arm toward the corpotentorium. The tremendous development 
of the caudal part is due to the need of a strong support for the dorsal 
surface, which bears a prominent horn used in fighting. 

The form and size of the metatentorium is quite decidedly indicated 
by the position of the metatentorinae. Those genera possessing primitive 
metatentorinae are very apt to possess the primitive type of metaten- 
torium, one that is short and simple, as Limulodes (Fig. 469), Sphaerius 
(Fig. 470), Anchicera (Fig. 535), Philothermus (Fig. 529), Melanoph- 
thalmus (Fig. 530), and Sphindus (Fig. 547). It is significant to note that 
all of these genera are very small in size. The cephalic migration of the 
metatentorinae is due to a similar movement of the metatentoria. In 
those genera in which the metatentorinae have migrated from their primi- 
tive position near the occipital foramen, the metatentoria are found more 
or less deeply invaginated along the gular sutures, the sutures being the 
products of these invaginations. In most genera the metatentoria advance 
but little or not at all farther cephalad than the metatentorinae, but there 
are some exceptions, in which the metatentoria taper gradually, as in 
Helichus (Fig. 503), Cyphon (Fig. 509), Lyctus (Fig. 546), and all of the 
Scarabaeoidea, except Pseudolucanus (Fig. 555). In those genera in. 
which the gular sutures are confluent on the meson, the gula itself is simply | 
invaginated, becoming a part of the metatentorium. The same type of 
development has taken place in Necrophorus (Fig. 460), Scaphidium 
(Fig. 471), Hister (Fig. 473), Phengodes (Fig. 470), Chauliognathus (Fig. 
477), and Georyssus (Fig. 506), as in the Rhynchophora. In Necrophorus, 
Phengodes, Chauliognathus, Eupsalis (Fig. 573) and Thecesternus (Fig. 
581), the line of fusion of the invaginations of the two sides has disappeared. 
In Chauliognathus the invagination is greatly reduced, and in Phengodes 
nothing remains but a mere line. These two latter genera seem to show a 
greater specialization of the gular region than any other genera studied. 
A correspondingly deeper invagination of the ring-like plate surrounding 
the inside periphery of the occipital foramen has occurred with that of the 
gula. The whole phenomenon appears to be due to an especially strong 
cephalic pull on the metatentoria. This can be readily understood in the 
case of the Rhynchophora, in which the elongation of the snout would 
encourage this result. A second force may play a part here, that of the 
narrowing of the snout, which might assist in the enfoldment of the gula. 

A large number of genera, scattered throughout the series of families, 
possess prominent projections along the mesal margins of the metatentoria, 
caudad of the corpotentorium, as those of Cybister (Fig. 451), Necrobia 
(Fig. 480), Glischrochilus (Fig. 517), Phyconomus (Fig. 519), and Boros 
(Fig. 539). Some of these projections have distinct tendons attached to 
them, as in Scaphidium (Fig. 471), Parandra (Fig. 557), Derobrachus 
(Fig. 558), Donacia (Fig. 562), and Criocerus (Fig. 564). Prominent 


38 ILLINOIS BIOLOGICAL MONOGRAPHS (38 


lateral projections are present in Lyctus (Fig. 546), Osmoderma (Fig. 553), 
Parandra, Glycobius (Fig. 560), Rhynchites (Fig. 577), Epicaerus (Fig. 
579), and Thecesternus (Fig. 581). Passalus (Fig. 556) is peculiar in the 
possession of a large well chitinized secondary bridge arising from the 
mesal margin of the metatentoria. 

Owing to the simplicity of form of a structure like the corpotentorium, 
but little change is indicated in it through most of the genera. The hypo- 
thetical type shows this structure to be a rather narrow simple band (Fig. 
443). Such is fairly characteristic of the vast majority of forms. The 
corpotentorium is sometimes very broad, as in Ptinus (Fig. 543), Bostrichus 
(Fig. 545), Parandra (Fig. 557), Derobrachus (Fig. 558), Glycobius (Fig. 
560), and Eupsalis (Fig: 573). In contrast are many that are quite slender 
and arched, as Dineutes (Fig. 452), Stenus (Fig. 463), Hister (Fig. 473), 
Georyssus (Fig. 506), and Mycetophagus (Fig. 527). The form of these 
latter has evidently resulted from the narrowing of the space between the 
metatentoria. An exceptionally large number of genera have only a 
rudimentary corpotentorium, or none at all, as in all of the Lampyroidea 
except Trichodes (Fig. 479) and Necrobia (Fig. 480), Epicauta (Fig. 487), 
Macrosiagon (Fig. 486), all of the Elateroidea, Psephenus (Fig. 502), 
Rhysodes (Fig. 514), Phalacrus (Fig. 533), Hippodamia (Fig. 534), and Ar- 
thromacra (Fig. 540). The reasons for the loss of the corpotentorium are 
not always evident, though in most cases, either the arms of the tentoria 
have expanded and approximately met on the meson, as in Rhysodes and 
Plesiocis (Fig. 548), or the arms are directed towards the meson and meet 
there, as in Connophron (Fig. 462) and all of the Elateroidea, or the 
pharynx rests snugly between the tentorial arms, as is so perfectly found 
in Chauliognathus (Fig. 477), where the pharynx is wedged so tightly 
between them that the whole seems like one piece, all of which conditions 
supply firmness to the tentorial arms and obviate the necessity for a corpo- 
tentorium. Of the Rhynchophora, Eurymycter (Fig. 575), Epicaerus 
(Fig. 579), Platypus (Fig. 583) and Lixus (Fig. 580) possess no corpoten- 
torium. Scolytus (Fig. 584) possesses a very rudimentary one. The dis- 
appearance of the corpotentorium can best be explained in the case of the 
Rhynchophora by the fusion of the metatentoria into one solid plate that 
needs no added support. The corpotentorium of most of the Ceramby- 
coidea is a delicate membranous structure. A common modification of 
the corpotenterium is the mesal projections on its cephalic border, as in 
Tachinus (Fig. 460), Cephaloon (Fig. 483), Tomoxia (Fig. 485), Phenolia 
(Fig. 510), and Philothermus (Fig. 529). 

A structure of the tentorium that shows perhaps a greater variability 
in form than any other is the laminatentorium, which appears in a great 
array of shapes and sizes, from the forming of a perfect and broad bridge 
to total disappearance. When the two sides of the laminatentorium meet 


39] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 39 


on the meson, the mesal margins of the laminatentorium very frequently 
are bent ventrad, producing a projection. Examples of this development 
are seen in Calosoma (Fig. 446), Cybister (Fig. 451), Necrophorus (Fig. 
460), Aleochara (Fig. 467), Heterocerus (Fig. 505), Dermestes (Fig. 511), 
and Endomychus (Fig. 532). Genera that show the laminatentorium as 
hardly more than touching on the meson are Peltodytes (Fig. 450), Scaph- 
idium (Fig. 471), Neopyrochroa (Fig. 481), Notoxus (Fig. 493), Psephenus 
(Fig. 502), Cucujus (Fig. 520), Penthe (Fig. 542), and most of the Scara- 
baeidae. The reduction of the laminatentorium takes place so gradually 
that it is hard to tell when it has completely disappeared. There seems to 
be no indication of it in Limulodes (Fig. 469), Collops (Fig. 478), Pseudo- 
cistela (Fig. 536), Hyporphagus (Fig. 541), Sphindus (Fig. 547), and others. 
In Tomoxia (Fig. 485), Pytho (Fig. 490), Alaus (Fig. 498), Tharops (Fig. 
499), Throscus (Fig. 500), and others, there is no laminatentorium. The 
pretentorial arms curve towards the meson and serve a similar purpose. 
The laminatentorium of Tachinus (Fig. 460) and Epicauta (Fig. 487) is in 
the form of a lobe. That of Psephenus (Fig. 502), Dichelonyx (Fig. 550), 
and Pelidnota (Fig. 551), possesses two long sharp cephalic projections. 

Arising from the dorsal surface of each pretentorium cephalad of the 
laminatentorium and usually extending towards the dorsal surface of the 
head is a projection of variable form, the supratentorium. Its generalized 
condition would show a rather distinctly chitinized structure, with an 
expanded ventral end that gradually narrows, then expands flat-like against 
the ental surface of the head-wall. This kind of structure is found in a 
very large number of genera, as all of the Adephaga except Peltodytes 
(Fig. 450), the Hydrophilidae, Leptinus (Fig. 459), all of the Staphylinoidea 
except Aleochara (Fig. 467), and Hister (Fig. 473), Pytho (Fig. 490), 
Nosodendron (Fig. 513), Languria (Fig. 522), Megalodacne (Fig. 523), 
Derobrachus (Fig. 558), and others. The supratentorium is a surprisingly 
persistent structure considering the large number of genera that possess 
it in a more or less rudimentary state. The broken ends of the tentoria of 
Eupsalis (Fig. 573), Lixus (Fig. 580), and Sphenophorus (Fig. 582), are 
expanded, which expansion may include a part of the supratentoria. This 
seems reasonable to believe when a rudimentary one is evidently present in 
Rhynchites (Fig. 577) and Attelabus (Fig. 578). Sphenophorus is peculiar 
in having the lateral margins of the tentoria fused to the oculata. The 
head-capsule of this genus is suddenly constricted at this point, which 
probably placed the tentorium and head-wall in contact, a fusion finally 
resulting. The supratentoria of Cucujus (Fig. 520) and Passalus (Fig. 
~.556) are stout structures, but extremely short. In the former, this condi- 
tion is due to the flatness of the head, in the latter, to the unusually close 
proximity of a part of the pretentoria to the dorsal surface. 


40 ILLINOIS BIOLOGICAL MONOGRAPHS [40 


SOME PHYLOGENETIC CONSIDERATIONS 


With the hypothetical type of coleopterous head in mind, it is possible 
to note the lines of development that have taken place within the various 
groups. Structures have developed away from the primitive condition 
with varying degrees of rapidity, and sometimes in different directions. 
It is difficult from this study to decide on the amount of importance to 
attach to the change that may take place in a particular structure, and to 
average the degree of primitiveness as a whole of the development of the 
structures characteristic of a group, and to indicate with precision the 
place in the primitive scale of each group. As previously mentioned, owing 
to the wide field covered in this investigation it was impossible to find 
time to study a large representation of genera within each family. Such 
a study should help one considerably in reaching clearer conclusions as to 
the arrangement of the genera in the primitive scale. Using this study 
as a basis, it is quite possible, however, to discuss the relative importance 
of the structural changes exhibited by the different groups, and to suggest 
possible inconsistencies in the present arrangement of certain genera. 
Statements made in the following discussion are based only on this study. 

The characteristic possession by the Adephaga (Figs. 2-10, 23-24, 
150-158, 297-305, 444-452) of the occipital suture, of complete epicranial 
arms, of a generalized position of the antennariae and of the pretentorinae, 
of a generalized form of labrum, and of tentorium, would force such families 
as the Cicindelidae, Carabidae, Amphizoidae and Omophronidae into a 
primitive place in the phylogenetic scale, in spite of their specialized ventral 
surface. No other large group shows as many primitive characters. The 
genera of the above mentioned families show a great similarity in all their 
structures and must be closely related. Of these families Omophronidae 
possibly possesses the most generalized dorsal surface, though the occipital 
suture in Omophron is not nearly complete, and does not show on this 
surface. Omophron can hardly hold an intermediate position between 
the Carabidae and the Haliplidae, for the latter family, as represented by 
Peltodytes, shows little similarity with any other family of the Adephaga. 
The form of the head is distinctly specialized, being globular, with enor- 
mous eyes, and the mouth-parts and the very small labrum are directed 
distinctly ventrad. The occipital suture is probably lacking, the epicranial 
suture is shorter than in any other genus of the Adephaga. On the ven- 
tral surface, the metatentorinae extend only half-way between the oc- 


41] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 41 


cipital foramen and the submentum, and the gular sutures extend no 
farther cephalad, whereas in all the other genera of the Adephaga the meta- 
tentorinae are close to the submentum and complete gular sutures are 
present. Finally, the tentorium of Peltodytes is not so well developed, 
and the supratentoria are small and do not reach the ental surface of the 
head-wall. In all other genera of the Adephaga the tentorium is large 
and strongly chitinized in all its parts. The Dytiscidae and Gyrinidae 
are very similar fundamentally, and differ from other adephagous families 
in the position on the ventral aspect of such structures as the antennariae 
and the pretentorinae, and by a rudimentary or absent occipital suture. 
The instability of the epicranial suture is well illustrated by the case of the 
two closely related genera, Dytiscus and Cybister, the former possessing 
complete, distinct arms, and a considerable part of the caudal end of the 
stem, the latter incomplete and rather indistinct arms and no part of the 
stem. The Dytiscidae and the Gyrinidae are undoubtedly more special- 
ized than the first four families of the Adephaga. 

The Hydrophiloidea (Figs. 11-14, 159-166, 306-309, 453-456) show 
by the form and texture of the heads of Hydrous and Hydrophielus that 
they are quite similar to those of the Dytiscidae and Gyrinidae, being 
broad and short, and strongly chitinized. The antennariae and preten- 
torinae of these two species have migrated ventrad, as in the other two 
families. The metatentorinae, the gula, and the tentorium are also al- 
most identical in form and condition. These species are evidently very 
closely related to the Dytiscidae and Gyrinidae. Hydraena is not so simi- 
lar, the dorsal surface of its head being more like that of the typical Carab- 
idae in shape and position of the parts. The gular sutures are short, 
as in Peltodytes. The head of Hydroscapha, its shape, the course of the 
epicranial arms, position of pretentorinae and antennariae, is distinctly 
like that of Omophron. 

The genera of the Silphoidea (Figs. 15-21, 163-169, 310-316, 457-462) 
show many inconsistencies. The dorsal and ventral surfaces and the endo- 
skeleton of no two genera are nearly alike. Necrophorus possesses the 
most generalized dorsal surface, which is very like that of the first four 
families of the Adephaga; Clambus, perhaps the most specialized, being 
distinctly consolidated. On the other hand, Necrophorus possesses the 
most specialized ventral surface present in this superfamily. The gular 
sutures are complete, and for more than half their extent meet on the meson. 
In contrast, there are practically no gular sutures in Connophron, a scyd- 
maenid, and Molamba, a corylophid. No greater extremes of this surface 
can be found within the limits of any other superfamily. The tentorium 
exhibits just as great extremes in development. That of Leptinus is quite 
generalized; that of Necrophorus well developed but specialized, owing to 
the invagination of the gula; that of Connophron with no corpotentorium 


42 ILLINOIS BIOLOGICAL MONOGRAPHS [42 


nor laminatentorium and rudimentary supratentorinae; that of Molamba 
the most rudimentary tentorium of any genus included within this study. 
No clearer illustration of the difficulties of indicating relationship can be 
shown than that exhibited by the families of the Silphoidea. 

A study of the Staphylinoidea (Figs. 22, 25-35, 170-181, 317-328, 463- 
473) shows that the various genera of the Staphylinidae have considerable 
homogeneity. Tachinus departs the most from the characteristic condi- 
tion, in possessing a much more generalized dorsal surface than the other 
members of this family. The Staphylinidae possess a tentorium and a 
ventral surface similar on the whole to that of the Adephaga and the 
Hydrophiloidea. Tachinus, through the added similarity of its dorsal 
surface, would seem to bear a particularly close relationship to these 
groups. The Sphaeriidae, as represented by Sphaerius, and the Ptilidae, as 
represented by Limulodes, possess a primitive condition of the metaten- 
torinae, while Scaphidium and Hister possess confluent gular sutures. 
The Pselaphidae, as represented by Pilopius, and the Clavigeridae, as 
represented by Fustiger, in form of head and character of the ventral surface 
and tentorium show a close relationship to Connophron. The irregu- 
larities of structure displayed by the families of this group are nearly as 
great as those displayed by the families of the Silphoidea. Both of these 
superfamilies probably need considerable revising. 

All of the genera of the Cantharoidea (Figs. 36-42, 182-190, 329-335, 
474-480) possess complete epicranial arms and dorsal portion of the anten- 
nariae, and lack of corpotentorium, except the Cleridae and the Coryne- 
tidae, represented by Trichodes and Necrobia respectively. All possess a 
complete gula except the latter genera and Collops, the representative of 
the Melyridae. This superfamily can be divided into three subgroups. 
One group will include the Lycidae and Lampyridae, characterized by a 
globular head, short broad gula, and absence of the pretentorinae. A 
second group will include the Phengodidae and the Cantharidae, char- 
acterized by a longer and flatter head and longer gula. The third group 
will include the Cleridae and the Corynetidae, possessing short incomplete 
arms, incomplete gular sutures, and a well developed corpotentorium. 
Collops does not seem to fit in very well anywhere, though this genus, 
through the form of its dorsal surface and tentorium may possibly lean 
towards the second group. Cantharis, of the second group, is peculiar in 
possessing a normal gula, whereas in the other forms the gula is rudimen- 
tary, though in all other respects this genus is like the other members of 
this group. The first and second groups are no doubt closely related. The 
latter is probably the more generalized, possessing a dorsal surface resem- 
bling to a marked extent the dorsal surface of the Carabidae. The gula, 
in so far as it is complete, also resembles the condition of this structure in 
the families of the Adephaga, and particularly in Necrophorus, of the 


43] THE HEAD-CAPSULE OF COLEOPTERA—STICKN EY 43 


Silphoidea. It has, however, developed much farther, even, than in 
Necrophorus, being not only invaginated, but reduced to a more or less 
rudimentary state. The first group probably evolved from the second by 
the change in the shape of the head, due to the enormous development of 
the compound eyes and the loss of much of the gular region, which has 
probably fused with the cervix. Parallel with these changes, the preten- 
toria shifted their position so that they could better support the globular 
head, and came to assume the direction ordinarily assumed by the supra- 
tentoria of other genera. The third group would appear to be more 
closely related to the Mordelloidea than to this superfamily. The condi- 
tion of the epicranial suture, the position of the antennariae, preten- 
torinae, and metatentorinae, the degree of development of the gula and 
tentorium, would all favor this assumption. 

The representatives of the Lymexyloidea (Figs. 43-44, 191-192, 336- 
337, 481), two families of this group, are not very similar. Hylecoetus 
has a head that is fairly compact, directed a little ventrad, the cervix 
possessing a cervepisternum, and a well developed tentorium. The 
head of Micromalthus is more compact than that of Hylecoetus, directed 
cephalad, there is no sclerite in the cervix, and the tentorium is rudi- 
mentary. As the superfamily stands, both could be placed in the Cu- 
cujoidea. 

The representative of the Cupesoidea (Figs. 45, 193, 338, 482) studied 
does not show any particular peculiarities of structure of the head that 
would entitle it to be placed in a separate superfamily. It can be very 
readily included with the Mordelloidea, for approximately the same reasons 
as the Cleridae and Corynetidae. 

The genera of the Mordelloidea (Figs. 46-57, 194-205, 339-350, 483- 
494) show considerable homogeneity. Most of them possess heads that 
are elongate, with a generalized dorsal surface and a large postclypeus and 
labrum, both on the same general level with the rest of the dorsal surface. 
The epicranial suture, however, shows considerable instability, sometimes 
showing complete arms and stem, as in Epicauta, while in others the epi- 
cranial suture may be extremely reduced, as in Macrosiagon. If these 
two genera are at all related, the condition of the epicranial suture can 
hardly throw any light on the degree of relationship. On the other 
hand, the metatentorinae are stable in position, and are located almost 
uniformly about half-way between the occipital foramen and the sub- 
mentum. Another characteristic feature is the fact that most of the 
genera possess heads that are distinctly constricted at their caudal ends 
to form a neck. The Oedemeridae, the Cephaloidae, the Pyrochroidae, 
the Pedilidae, the Anthicidae, and possibly the Cupesidae and Meloidae, 
seem particularly closely related, through the possession of similarly shaped 
heads, whose caudal ends are distinctly constricted, of a generalized dorsal 


44 ILLINOIS BIOLOGICAL MONOGRAPHS [44 


surface, of compound eyes that are usually more or less emarginated, of a 
ventral surface whose structures are practically in a similar condition, 
and of a tentorium that is alike throughout, with the exception of the 
Meloidae, in which the corpotentorium is absent. Though the dorsal 
surface of the Mordelloidea resembles to a considerable extent that of such 
families as the Carabidae and Cantharidae, yet this surface differs so 
widely in closely related groups that we can hardly place too much impor- 
tance on the resemblance here. What seems to be far more important 
is the totally different condition of the ventral surfaces in the Mordelloidea 
and the Carabidae, for instance. In the former the gular sutures and the 
metatentorinae extend uniformly half way between the occipital foramen 
and the submentum; in the Carabidae the gular sutures extend the whole 
distance between these parts and the metatentorinae, nearly to the sub- 
mentum. The Mordelloidea and such groups as the Adephaga and 
Hydrophiloidea do not appear to be nearly related. 

The members of the Elateroidea are on the whole (Figs. 58-64, 206— 
212, 351-357, 495-501) homogeneous with the exception of the Bu- 
prestidae. The pretentorinae and the antennariae are located on the dorsal 
surface, and the epicranial arms extend no farther caudad than the pre- 
tentorinae. On the ventral aspect, the metatentorinae extend but little 
cephalad of the occipital foramen, and the gular sutures no farther. The 
corpotentorium is lacking in all except Cebrio and Euthysanius. In the 
Buprestidae, on the other hand, the pretentorinae and antennariae have 
migrated distinctly ventrad, and are not visible at all from the dorsal 
surface. The gular sutures extend the whole distance between the oc- 
cipital foramen and the submentum, and there is a distinct corpotentorium. 
Considering these points, the Buprestidae are hardly closely related to 
the rest of the Elateroidea. 

With the exception of the Georyssidae, the members of the Diyopbided 
(Figs. 65-69, 213-217, 358-362, 502-506) appear to be fairly homogeneous. 
The chief characteristics are very prominent widely separated metaten- 
torinae, located very near the occipital foramen, and a very broad sub- 
mentum. The ventral surface of the Georyssidae, as represented by 
Georyssus, is totally different. In this family the gular sutures extend 
nearly to the submentum, and are confluent through practically their 
entire extent. The metatentorinae cannot be definitely located. Georys- 
sus would appear to be related to Hister, both through the condition of 
the gula, of the tentorium, and of the dorsal surface. The general ap- 
pearance of the ventral surface in the Dryopoidea is much like that of the 
Elateroidea, and in other characteristics they are not unlike. These two 
superfamilies are probably related. 

The representatives of the four families of the Dascilloidea (Figs. 
70-73, 218-221, 363-366, 507-510) studied are similar in structure. There 


45] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 45 


are no outstanding features that would warrant placing them in a separate 
superfamily. They are negative enough in their characteristics to fit in, 
perhaps, in a number of other superfamilies, such as the Mordelloidea, 
Cucujoidea, and Tenebrionoidea. 

The representatives of the three families of the Byrrhoidea (Figs. 
74-76, 222-224, 367-369, 511-513), the Dermestidae and the Byrrhidae 
studied, Dermestes and Byrrhus, do not seem to differ decidedly from 
one another, but the Nosodendronidae, represented by Nosodendron, 
may fit in better in some other group, such as the Dryopoidea. They 
resemble the members of this latter group in the position of the meta- 
tentorinae and in the form of the submentum. In Nosodendron, the 
metatentorinae are almost adjacent to the occipital foramen, with a mem- 
branous area included between them. That part of the metatentorium 
surrounding the periphery of the occipital foramen projects deep into 
the head. The supratentoria are well developed. None of these charac- 
teristics are possessed by the other two genera studied. 

The representative of the single family of this superfamily (Figs. 
77, 225, 370, 514) studied, Rhysodes, shows distinct peculiarities in the 
structure of its head, such as an extremely thick chitinous head-wall, a 
fibrous condition of the cervix, an arrow-shaped head, enormously de- 
veloped submentum, and very small mouth-parts. Its relationships are 
not at all clear. 

The members of the Cucujoidea (Figs. 78-98, 226-246, 371-391, 
515-535) show on the whole a short broad head-capsule, a distinct ventral 
migration of the antennariae and pretentorinae, the degeneration of the 
epicranial arms, and a slight migration of the metatentorinae from the 
occipital foramen. There is some variation in the dorsal aspect. The 
genera belonging to the Mycetophagidae, the Mycetaeidae, the Melan- 
ophthalmidae, the Endomychidae, and perhaps those of a few other families, 
possess dorsal surfaces that strongly resemble the dorsal surface of the 
Mordelloidea. In Derodontus and Philothermus, a colydiid, the anten- 
nariae and the pretentorinae are both on the dorsal aspect, located con- 
siderably caudad. The ventral aspect of all the members of the group, 
however, is strikingly similar. The tentorium is fairly uniform through- 
out the group except in Tenebroides and Phalacrus, in which the preten- 
torium has distinctly degenerated, due probably to the heavy chitiniza- 
tion of the head-wall. In the shape of the head and the condition of the 
metatentorinae and the gular sutures, the Cucujoidea show a similarity 
to the Mordelloidea, and to the superfamily Tenebrionoidea. 

There are no particular characteristics of the head-capsule that would 
separate the Tenebroidea (Figs. 99-111, 247-259, 392-404, 536-548) 
from the typical Mordelloidea. For instance, the dorsal and ventral 
surfaces and the endoskeleton of Arthromacra, Pseudocistela, and Penthe, 


46 ILLINOIS BIOLOGICAL MONOGRAPHS [46 


are almost exactly like these parts of such genera of the Mordelloidea as 
Epicauta, Cephaloon, and Macratria. The corpotentorium of Arthro- 
macra and Epicauta is, however, lacking. The structure of the various 
parts of the head-capsule of the representatives of the Bostrichidae varies 
considerably. The epicranial arms are complete in Bostrichus, Lyctus, 
Plesiocis, and Sphindus. With the exception of Sphindus these families 
show a distinct ventral migration of the antennariae and pretentorinae. 
In contrast, Ptinus and Sitodrepa do not possess complete arms, and the 
antennariae and pretentorinae are located more dorsad, markedly so in 
the former. On the ventral surface, there is considerable variation in 
the position of the metatentorinae. The tentorium also varies a great 
deal. This is probably not a very homogeneous group. Sphindus seems 
to be structurally more similar to Sphaerius than any other genus studied. 

The Scarabaeoidea (Figs. 112-119, 260-267, 405-413, 549-556) is a 
very homogeneous group, characterized by a heavy chitinization of the 
head-wall, degeneration of the epicranial suture, ventral migration of the 
antennariae and the pretentorinae, and a complete gula, except in Pseudo- 
lucanus, in which the gular sutures extend no more than half the distance 
between the occipital foramen and the submentum. In the development 
of the ventral surface and perhaps the tentorium, the Scarabaeoidea 
should be classed with the Adephaga and related groups. 

The Cerambycoidea (Figs. 120-135, 268-283, 414-429, 562-572) is 
also a very homogeneous group, characterized by a weak chitinization of 
the head-wall, a distinct dorsal position of the antennariae and the pre- 
tentorinae, and a more or less well developed epicranial suture. The 
gular sutures are generally short. The tentorium is delicate and mem- 
branous throughout. 

The members of the Rhynchophora (Figs. 136-148, 284-296, 430-442, 
573-585) may or may not possess a snout. They may or may not possess 
confluent gular sutures. When they do, the condition is the same as in other 
Coleoptera, except that the invaginations are apt to be more extensive. 
They may or may not possess a labrum. There is no definite character of 
the head-capsule by which the Rhynchophora as a group can be separated 
from other Coleoptera. The affinities of this group are not at all clear. 

The condition of the dorsal surface throughout the groups is most 
variable, and can be relied upon but little to furnish evidence of the degree 
of relationship. On the ventral surface the condition is much more 
stable, and probably much more reliable in indicating affinities. The 
tentorium is less variable than the dorsal surface, and less stable than 
the ventral surface. Weighing the evidence presented in this study, two 
large groups of most of the families can be made. The Lymexyloidea, 
the Cupesoidea, the Mordelloidea, the Elateroidea, the Dryopoidea, the 
Dascilloidea, the Byrrhoidea, the Cucujoidea, the Tenebrionoidea, 


47] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 47 


and the Bostrichoidea should probably be grouped together, while the 
characteristic families of the Cantharoidea, the Staphylinoidea, and the 
Silphoidea should perhaps be grouped with the Adephaga and Hydro- 
philoidea. The Scarabaeoidea may also be included in this latter group. 
The affinities of the Cerambycoidea and the Rhynchophora are too vague 
to include either in the two larger groups. 


48 ILLINOIS BIOLOGICAL MONOGRAPHS [48 


SUMMARY 


1. This investigation deals with the homology of all the structures of 
the head-capsule of one or more representatives of one hundred and five 
of the one hundred and nine families of Coleoptera listed by Leng in his 
recent catalogue. One hundred and forty-six genera have been studied 
and figured, nearly all representing different important subgroups. 

2. This serial study has made it possible to identify the same structures 
in a wide series of forms, and to definitely fix the homology of all the parts 
of the head-capsule. 

3. Hypothetical types have been constructed, based on the structure 
of the head-capsule of generalized insects and Coleoptera. These show 
the Coleoptera to have developed in general a consolidation of sclerites 
and a heavier chitinization of the head wall, a compacting of the head as a 
whole, and an approximation of the dorsal and ventral movable parts 
at the cephalic end. 

4, The epicranial suture has been identified in all but two of the genera 
studied. It has proved a great aid in determining the limits of neighboring 
parts. What may appear to be a distinct epicranial suture may not even 
be a suture. It is sometimes distinctly invaginated. Its identity can 
only be definitely fixed by determining the location of the pretentorinae, 
which are always associated with it. 

5. The limits of the vertex are dependent upon the position of the 
epicranial suture. In the Rhynchophora nearly all of the snout belongs 
to the vertex. 

6. The unmodified occipital suture has been identified only in the 
Adephaga. The cephalic end on the ventral surface is always represented 
by part of a curving ridge, which is present in all but a few genera. 

7. The supratentorinae have been identified in a few genera, nearly 
all of which belong to the Staphylinoidea. 

8. The pretentorinae are the great landmarks of the head-capsule 
and have been identified in all but two genera. They are, in the vast 
majority of genera, located near the cephalic end of the epicranial arms. 
A definite determination of the pretentorinae cannot always be made with- 
out an ental examination of the head. 

9. The size and form of the front is dependent upon the position of the 
epicranial arms. In the Cerambycoidea it is large. In many genera, 
as illustrated by Omophron, Harpalus, and Tachinus, it is partly or wholly 
invaginated. It may probably be rudimentary or wholly lost in many 
genera in which the mesal parts of the epicranial arms have disappeared. 


49] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 49 


10. What has been called the clypeal suture in such genera as Cicindela 
and Harpalus is not even a suture, but the line of invagination of the front. 

11. The clypeus is always divided into the postclypeus and the pre- 
clypeus. The preclypeus is with one exception always distinctly mem- 
branous. It may be as large or larger than the labrum. 

12. There is a distinct clypealia present in the Coleoptera and in 
widely separated groups, such as the Adephaga and the Cerambycoidea. 

13. The labrum may be indistinctly determined in both Rhynchophora 
and other Coleoptera. It may also be quite distinct in some Rhyncho- 
phora where it is considered to be absent. 

14. The submentum is always located distinctly cephalad of the oc- 
cipital foramen, with a chitinized area between it and the foramen. 

15. The metatentorinae may be located on the cephalo-lateral border 
of the occipital foramen, as in generalized insects, or they may be far 
cephalad of this location. 

16. All that region between the occipital foramen and the submentum 
is a part of the postgenae, produced by the fusion on the meson of the mesal 
margins of the postgenae. 

17. The gular sutures result from the cephalic migration of the meta- 
tentorinae. 

18. The gula is that area included between the gular sutures, and is, 
therefore, derived from the postgenae. The majority of the Coleoptera 
possess a gula that extends no more than half the distance between the 
occipital foramen and the submentum. 

19. The tentorium of the Coleoptera is typically quite similar in form 
and development to that of generalized insects. Frequent modifications 
are loss of chitinization, loss of corpotentorium and laminatentorium. 
Occasionally the pretentorium may be rudimentary. The functions of 
the absent parts are assumed by other parts of the tentorium, or by the 
pharynx, or the head may be so compact and chitinized that a tentorium 
is no longer needed. 

20. The cephalic migration of the submentum, and the subsequent 
formation of an indistinguishable area between it and the occipital fora- 
men is due either to the migration caudad of the occipital foramen or to the 
cephalic pull on the mouth-parts or to both. The cephalic migration of 
the metatentoria and, therefore, the metatentorinae, with consequent pro- 
duction of the gula, is probably due to the cephalic pull on the tentorium to 
furnish a firmer support for the muscles and tendons of the mouth-parts. 


50 ILLINOIS BIOLOGICAL MONOGRAPHS [50 


BIBLIOGRAPHY 


BERLESE, A. 
1909. Gli Insetti. 1: 75-114. Milano. 
Bovine, A., and CHAMPLAIN, A. B. 

1920. Larvae of North American beetles of the family Cleridae. 

Proc. U. S. Nat. Mus., 57:575-649; pl. 42-53. 
Comstock, J. H. 
1893. Evolution and taxonomy. Wilder Quarter Century Book. 
Pp. 37-113; 3 pls. 
Comstock, J. H., and Kocw, C. 
1902. The skeleton of the head of insects. Amer. Nat., 36:13-45; 29 figs. 
CRAIGHEAD, F. C. 

1920. Biology of some Coleoptera of the families Colydiidae and Bothrideridae. Proc. 

Ent. Soc. Wash., 22:1-13; 2 pls. 
Crampton, G. C. 

1917. The nature of the veracervix or neck region in insects. Ann. Ent. Soc. Am., 
10:187-197. 

1920. A comparison of the external anatomy of the lower Lepidoptera and Trichoptera 
from the standpoint of phylogy. Psyche, 27:23-34; pl. 2-3. 

1921. The sclerites of the head, and the mouthparts of certain immature and adult 
insects. Ann. Ent. Soc. Am., 10:65-103; 86 figs. 

1920. La nervation alaire des Coleopteres. Ann. Soc. Ent. Fr., 89:1—50; 30 figs.; 3 pls. 

GacE, J. Howarp. 
1920. The larvae of the Coccinellidae. Ill. Biol. Monographs, 6:49 pp.; 6 pls. 
GaBAN, C. J. 

1911. On some recent attempts to classify the Coleoptera in accordance with their 
phylogeny. The Entomologist, 45:121-125, 165-169, 214-219, 245-248, 259- 
262, 312-314, 348-351, 392-396; 7 figs. 

GANGLBAUER, L. 
1892-1904. Die Kafer von Mitteleuropa. Vol. 1-4, Pt. 1. Wien. 
HANDLIRSCH, A. 

1906-1908. Die Fossilen Insekten und die Phylogenie aS Rezenten Formen. Pp. 

1271-80. Leipzig. 
Hopkins, A. D. 

1915. Preliminary lacerations of the superfamily Scolytoidea. Bul. U. S. Bur. Ent., 

Tech. Ser., No. 17, Pt. 2, pp. 165-237. 
Hystop, J. A. 

1917. The phylogeny of the Elateridae based on larval characters. Ann. Ent. Soc. 

Amer., 10:233-263; 10 figs. 
Kose, H. J. 

1901. Vergleichend morphologische Untersuchungen an Coleoptera nebst Grundlagen 
zu einem System und zur Systematik derselben. Beiheft Arch. Naturg., Fest- 
schrift Edward von Martens, 89-150; 2 pls. 

1908. Mein System der Coleopteren Zeitschr. fiir wissenschaftliche Insekten biologie, 
IV, p. 116-400. 


51) THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 51 


1911. Die Vergleichende Morphologie und Systematik der Coleopteren. Premier 
Congres international d’Entomologie, IT:41-68. 
LAMEERE, A. 
1900. Notes pour la classification des Coleopteres. Ann. Soc. Ent. Belg., 44:355-357. 
1903. Nouvelles notes pour la classification des Coleopteres. Ann. Soc. Ent. Belg. 
47:155-165. 
Le Conte, J. L., and Horn, G. H. 
1883. Classification of the Coleoptera of North America. Smithsonian Mis. Coll., 


No. 507. 
Lene, C. W. 
1920. Catalogue of the Coleoptera of America, north of Mexico. 470 pp. Mt. 
Vernon, N. Y. 


Morr, F. 
1918. Notes on the ontogeny and morphology of the male genital tube in Coleoptera. 
Trans. Ent. Soc. Lond., 1912:223-229; 10 pls. 
OrcHyMont, A. ’d 
1916. Notes pour la classification et la eer des Palpicornia. Ann. Soc. Ent. 
Fr., 85:91-106; 6 figs. 
PETERSON, A. 
1915. Morphological! studies on the head and mouth-parts of the Thysanoptera. Ann. 
Ent. Soc. Amer., 8:20-67; 7 pls. 
1916. The head-capsule and mouth-parts of Diptera. Ill. Biol. Monographs, 3:1-112; 
25 pls. 
Ritey, W. A. 
1904. The embryological development of the skeleton of the head of Blatta. Amer. 
Nat., 38:777-810; 12 figs. 
ScutopTE, J. C. 
1861-1883. De Metamorphosi Eleutheratorum Observationes: Bidrag til Insekternes 
Udviklings-historie. 2 vols.; 86 pls. Kjobenhaven. 
SHARP, D. 
1909. Insects. Cambridge Nat. Hist., 6:184-298. 
SHarp, D., and Murr, F. 
1912. The comparative anatomy of the male genital tube in Coleoptera. Trans. 
Ent. Soc. Lond., 1912:477-639; pl. 42-78. 
StTRAUSS-DuRCKHEM, H. E. 
1828. Considerations generales sur l’anatomie comparee des animaux articules, aux- 
quelles on a joint l’anatomie descriptive du hanneton vulgaire. Paris. 19+ 434 
pp. 10 double plates. 


LIBRARY 
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THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PEATE. 


54 


Fig. 
Fig. 
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ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE I 


DORSAL ASPECT OF THE HEAD 


. Hypothetical type. 

. Tetracha carolina. 

. Cicindela formosa. 

. Calosoma calidum. 

. Harpalus erraticus. 

. Amphizoa lecontet. 

. Omophron americanum. 
. Peltodytes 12-punctatus. 
. Cybister fimbriolatus. 

. Dineutes americanus. 
Hydraena marginicollis. 
. Hydroscapha natans. 

. Hydrous triangularis. 

. Hydrophilus obtusatus. 
15: 
. Brathimus nitidus. 

. Leptinus testaceus. 

. Necrophorus carolinus. 
. Clambus puberulus. 

. Connophron fossiger. 

. Molamba lunata. 

. Stenus flavicornis. 

. Harpalus erraticus, cross-section of cephalic end of the dorsal aspect of the head. 
. Harpalus erraticus, showing invagination of the front. 


Platypsyllus castoris. 


antacoila 
antafossa 
antacoria 
cervinotum 
compound eye 
clypofrons 
clypealia 
epicranial arm 
exoculata 
epicranial stem 
front 


fos 
fe 
l 
oc 
ol 
os 


pe 


fronto-clypeal suture 
frontal ridge 
labrum 

occiput 

oculata 
occipital suture 
preclypeus 
pretentorina 
postclypeus 
supratentorina 
vertex 


(54 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PEATE E 


56 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE II 


DORSAL ASPECT OF THE HEAD 


. Gastrolobium bicolor. 

. Creophilus villosus. 

. Tachinus fimbriatus. 

. Aleochara lata. 

. Pilopius lacustris. 

. Fustiger fuchsi. 

. Limulodes paradoxus. 

. Sphaerius politus. 

. Scaphidium quadriguttatum. 
. Sphaerites glabratus. 

. Hister memnonius. 

. Calopteron terminale. 

. Photinus pyralis. 

. Phengodes plumosa. 

. Chauliognathus pennsylvanicus. 
. Collops nigriceps. 

. Trichodes nutalli. 


. Necrobia rufipes. 

. Hylecoetus lugubris. 

. Micromalthus debilis. 

. Cupes concolor. 

antacoila f front t 
antafossa fe frontal ridge 
antacoria i labrum 
cervinotum pe preclypeus 
compound eye pn pretentorina 
clypealia po postclypeus 
epicranial arm sn supratentorina 


epicranial stem v vertex 


[56 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE iT 


A—STICKNEY a ta 
+ 3 : 


58 ILLINOIS BIOLOGICAL MONOGRAPHS 
EXPLANATION OF PLATE III 
DORSAL ASPECT OF THE HEAD 

Fig. 46. Cephaloon lepiurides. 

Fig. 47. Nacerda melanura. 

Vig. 48. Tomoxia bidentata. 

Fig. 49. Macrosiagon dimidiatum. 

Fig. 50. Epicauta marginata. 

Fig. 51. Eurystethus debilis. 

Fig. 52. Othnius sp. 

Fig. 53. Pytho planus. 

Fig. 54. Neopyrochroa flabellata. 

Fig. 55. Macratria murina. 

Fig. 56. Notoxus anchora. 

Fig. 57. Zonantes fasciatus. 

Fig. 58. Cebrio bicolor. 

Fig. 59. Euthysanius lautus. 

Fig. 60. Sandalus niger. 

Fig. 61. Alaus oculatus. 

Fig. 62. Isorhipis ruficornis. 

Fig. 63. Throscus chevrolati. 

Fig. 64. Chalcophora virginiensis. 

Fig. 65. Psephenus lecontei. 
aa antacoila fr frontal ridge 
af antafossa lL labrum 
ce compound eye pe preclypeus 
cl clypealia pn pretentorina 
ea epicranial arm po postclypeus 
es epicranial stem v vertex 


jf front 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA BA Ey eat 


¥, 


a 


< 
aw 


-e 4 
of 


By re ate 


w 
a) 


sented 
— 


59] 


. THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE. TV 


60 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE IV 


66. Helichus striatus. 
67. Stenelmis sinuata. 
68. Heterocerus undatus. 


69. Georyssus californicus. 


70. Eurypogon niger. 
71. Eucinetus morio. 
72. Cyphon ruficollis. 
73. Chelonarium errans. 
74. Dermestes lardarius. 
75. Byrrhus americanus. 


76. Nosodendron unicolor. 


77. Rhysodes americanus. 
78. Tenebroides sinuatus. 
79. Phenolia grossa. 


DORSAL ASPECT OF THE HEAD 


80. Glischrochilus fasciatus. 
81. Rhizophagus bipunctatus. 


82. Phyconomus marinus. 
83. Cucujus clavipes. 


84. Hemipeplus marginipennis. 


85. Languria mozardi. 
86. Megalodacne fasciata. 
87. Derodontus asculatus. 


aa antacoila 

af antafossa 

ce compound eye 
cl clypealia 

ea epicranial arm 
es epicranial stem 
f front 


fe frontal ridge 
1 labrum 

~p  preclypeus 
pn pretentorina 
po postclypeus 
pr precoila 

v vertex 


[60 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE IV 


61] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE V 


61 


62 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


88. 
89. 
90. 
91. 
92. 
93. 
94. 
95. 
96. 
97. 
98. 
99. 
100. 
101. 
102. 
103. 
104. 
105. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE V 
DORSAL ASPECT OF THE HEAD 


Anckhicera ephippiata. 
Byturus unicolor. 
Mycetophagus punctatus. 
Bothrideres geminatus. 
Philothermus glabriculus. 
Melanophthalma cavicollis. 
Phymaphora pulchelia. 
Endomychus biguitatus. 
Phalacrus politus. 
Hippodamia convergens. 
Adalia bipunctata. 
Pseudocistela brevis. 
Alobates pennsylvanica. 
Tenebrio molitor. 

Boros unicolor. 
Arthromacra aenea. 
Hyporphagus sp. 

Penthe obliquata. 


106. Ptinus brunneus. 

107. Sitodrepa panicea. 

aa antacoila fe frontal ridge 
a antafossa lL labrum 

é compound eye pe preclypeus 
l clypealia pn pretentorina 
@ epicranial arm po postclypeus 


§ epicranial stem 


sn supratentorina 


f front v vertex 


[62 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE V 


63] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE Vi 


63 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE VI 


DORSAL ASPECT OF THE HEAD 


108. Bostrichus bicornis. 

109. Lyctus planicollis. 

110. Sphindus americanus. 
111. Plesiocis cribrum. 

112. Aphodius fimetarius. 
113. Dichelonyx elongata. 

114. Pelidnota punctata. 

115. Strategus julianus. 

116. Osmoderma eremicola. 
117. Trox suberosus. 

118. Pseudolucanus capreolus. 
119. Passalus cornutus. 

120. Parandra brunnea. 

121. Derobrachus brunneus. 
122. Spondylis buprestoides. 
123. Glycobius speciosus. 

124. Tetraopes tetraophthalmus. 
125. Donacia piscatrix. 

126. Syneta ferruginea. 

127. Criocerus asparagi. 


aa antacoila f front 
af antafossa fe frontal ridge 


ce 
ch 
ol 

ea 
€0 
es 


compound eye lL labrum 
chitinized area pe preclypeus 
clypealia pn pretentorina 
epicranial arm po postclypeus 
exoculata v vertex 
epicranial stem 


[64 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE VI 


nage _ 
i ht ee ken 
} Dien dente eet eA =~ ter eathn 


jane ‘ey 


5 . 


ae , c be : ee aT a : - 


oo : ro mo &  ) a +f i‘ Wr ee Fare tte rare joo 
: rh 


66 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


128. 
129. 
130. 
i3f. 
132. 
133. 
134. 
135, 
136. 
137. 
138. 
155. 
140. 
141. 
142. 
143. 
144. 
145. 
146. 


147 
148 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE VII 
DORSAL ASPECT OF THE HEAD 


Cryptocephalus quadruplex. 
Chrysochus auratus. 
Leptinotarsa decemlineata. 
Diabrotica 12-punctata. 
Blepharida rhois. 
Anoplitis gracilis. 
Chelymorpha argus. 
Pachymerus gleditsiae. 
Eupsalis minuta. 
Ithycerus noveboracensis. 
Eurymycter fasciatus. 
Rhinomacer pilosus. 
Rhynchites bicolor. 
Attelabus analis. 
Epicaerus imbricatus. 
Lixus fimbriolatus. 
Thecesternus humeralis. 
Sphenophorus aequalis. 
Platypus flavicornis. 

. Scolytus quadrispinosus. 
. Dendroctonus valens. 


aa antacoila lL labrum 

af antafossa pe preclypeus 
an antacoria pn pretentorina 
ce compound eye po postclypeus 
cl clypealia pr precoila 

€a epicranial arm pi pretentorium 
es epicranial stem v vertex 

f front 


VOLUME VIII 


ILLINOIS BIOLOGICAL MONOGRAPHS 


PLATE Vil 


ERA 


HEAD-CAPSULE OF COLEOPT 


STICKNEY 


67| 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE VIII 


67 


68 ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE VIII 
VENTRAL ASPECT OF THE HEAD 


Fig. 149. Hypothetical type. 
Fig. 150. Tetracha carolina. 

Fig. 151. Cicindela formosa. 

Fig. 152. Calosoma calidum. 

Fig. 153. Harpalus erraticus. 
Fig. 154. Amphizoa lecontei. 

Fig. 155. Omophron americanum. 
Fig. 156. Peltodytes 12-punctatus. 
Fig. 157. Cybister fimbriolatus. 
Fig. 158. Dineutes americanus. 
Fig. 159. Hydraena marginicollis. 
Fig. 160. Hydroscapha natans. 
Fig. 161. Hydrous triangularis. 
Fig. 162. Hydrophilus obtusatus. 
Fig. 163. Platypsyllus castoris. 
Fig. 164. Brathinus nitidis. 

Fig. 165. Leptinus testaceus. 

Fig. 166. Necrophorus carolinus. 
Fig. 167. Clambus puberulus. 
Fig. 168. Connophron fossiger. 
Fig. 169. Molamba lunata. 

Fig. 170. Stenus flavicornis. 


aa = antacoila mt metatentorium 
af  antafossa oc — occiput 

an  antacoria os occipital suture 
ccp cervepimeron pa _postgena 

ccs cervepisternum pe _preclypeus 

cct cervisternum pl __paracoila 

ce compound eye pn _ pretentorina 
gu guia pr precoila 

gub gula bar pt pretentorium 
in invagination pil  postcoila 

inl line of invagination sm submentum 

l labrum v vertex 


mn metatentorina 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE VITI 


‘ 
POTN ke Bs 
h 
* 
, 
’ 
* 
s 


hein 
i 
} 
v 


ie 

\ 
ri 
com 


i 


— | 
. 


PLATE IX 


70 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


gud 
1m 
inl 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE IX 


VENTRAL ASPECT OF THE HEAD 


. Gasirolobium bicolor. 

. Creophilus villosus. 

. Tachinus fimbriatus. 

. Aleochara lata. 

. Pilopius lacustris. 

. Fustiger fuchsi. 

. Limulodes paradoxus. 

. Sphaerius politus. 

. Scaphidium quadriguitaium. 

. Sphaerites glabratus. 

. Hister memnonius. 

. Calopteron terminale. 

. Photinus pyralis. 

. Phengodes plumosa. 

. Chauliognathus pennsylvanicus. 
. Chauliognathus pennsylvanicus, cross-section, showing invagination of gula. 
. Cantharis bilineatus. 


. Collops nigriceps. 

. Trichodes nutalli. 

. Necrobia rufipes. 

. Hylecoetus lugubris. 

. Micromalthus debilis. 
antacoila l labrum 
antafossa mn metatentorina 
antacoria mt metatentorium 
cervepimeron os occipital suture 
cervepisternum pa postgena ~ 
cervisternum pe  preclypeus 
compound eye pl _ paracoila 
chitinized area pn  pretentorina 
epicranial arm pr precoila 
gula pt pretentorium 
gula bar pil postcoila 
invagination sm  submentum 
line of invagination v vertex 


1) 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE, LX 


72 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE X 


VENTRAL ASPECT OF THE HEAD 


. Cupes concolor. 

. Cephaloon lepturides. 

. Nacerda melanura. 

. Tomoxia bidentata. 

. Macrosiagon dimidiatum. 
. Epicauta marginata. 

. Eurystethus debilis. 

. Otknius sp. 

. Pytho planus. 

. Neopyrochroa flabellata. 
. Macratria murina. 

. Notoxus anchora. 

. Zonantes fasciatus. 

. Cebrio bicolor. 

. Euthysanius lautus. 

. Sandalus niger. 

. Alaus oculatus. 

. Isorhipis ruficornis. 

. Throscus chevrolati. 

. Chalcophora virginiensis. 
. Psephenus lecontez. 


antacoila mn metatentorina 
antafossa os occipital suture 
cervepimeron pa  postgena 
cervepisternum pe — preclypeus 
cervisternum pl paracoila 
compound eye pn pretentorina 
epicranial arm pr precoila 

gula pil postcoila 
invagination sm  submentum 
line of invagination v vertex 


labrum 


[72 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE X 


73] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XI 


73 


74 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XI 


VENTRAL ASPECT OF THE HEAD 


. Helichus striatus. 

. Stenelmis sinuata. 

. Heterocerus undatus. 

. Georyssus californicus. 
. Eurypogon niger. 

. Eucinetus morio. 

. Cyphon ruficollis. 

. Chelonarium errans. 

. Dermestes lardarius. 

. Byrrhus americanus. 

. Nosodendron unicolor. 

. Rhysodes americanus. 

. Tenebroides sinuatus. 

. Phenolia grossa. 

. Glischrochilus fasciatus. 
. Rhizophagus bipunctatus. 
. Phyconomus marinus. 

. Cucujus clavipes. 

. Hemipeplus marginipennis. 
. Languria mozardi. 

. Megalodacne fasciata. 

. Derodontus maculatus. 


antacoila od  odontoidea 
antafossa os occipital suture 
cervepimeron pa  postgena 
cervepisternum pe _ preclypeus 
cervisternum pl __paracoila 
compound eye pn  pretentorina 
epicranial arm pr precoila 

gula pil postcoila 

line of invagination sm submentum 
labrum v vertex 


metatentorina 


[74 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


\ 
BY 
= 


y 
\ 
v 
7 
/ 
/ 


SrICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE Xl 


75] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE Xi 


76 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XII 


VENTRAL ASPECT OF THE HEAD 


. Anchicera ephippiata. 

. Byturus unicolor. 

. Mycetophagus punctatus. 
. Bothrideres geminatus. 

. Philothermus glabriculus. 
. Melanopthalma cavicollis. 
. Phymaphora pulchelia. 

. Endomychus biguttatus. 

. Phalacrus politus. 

. Hippodamia convergens. 
. Adalia bipunctata. 

. Pseudocistela brevis. 

. Alobates pennsylvanica. 

. Tenebrio molitor. 

. Boros unicolor. 

. Arthromacra aenea. 

. Hyporphagus sp. 

. Penthe obliquata. 

. Ptinus brunneus. 

. Sitodrepa panicea. 


. Bostrichus bicornis. 

. Lyctus planicollis. 
antacoila mn metatentorina 
antafossa os occipital suture 
antacoria pa postgena 
cervepimeron pe preclypeus 
cervepisternum pl paracoila 
compound eye pn pretentorina 
epicranial arm pr _ precoila 
gula pt pretentorium 
invagination pil postcoila 
line of invagination sm  submentum 


labrum v vertex 


176 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XII 


77) 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XIII 


78 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XIII 


VENTRAL ASPECT OF THE HEAD 


. Sphindus americanus. 

. Plesiocis cribrum. 

. Aphodius fimetarius. 

. Dichelonyx elongata. 

. Pelidnota punctata. 

. Strategus julianus. 

. Osmoderma eremicola. 

. Trox suberosus. 

. Pseudolucanus capreolus. 
. Passalus cornutus. 

. Parandra brunnea. 

. Derobrachus brunneus. 

. Spondylis buprestoides. 

. Glycobius speciosus. 

. Tetraopes tetrophthalmus. 
. Donacia piscatrix. 

. Syneta ferruginea. 

. Criocerus asparagi. 

. Cryptocephalus quadruplex. 
. Chrysochus auratus. 

. Leptinotarsa decemlineata. 
. Diabrotica 12-punctata. 


antacoila of occipital foramen 
antafossa pa  postgena 
antacoria pe  preclypeus 
cervepimeron pl =paracoila 
cervepisternum pn pretentorina 
compound eye pr precoila 
epicranial arm pi  pretentorium 
gula pil postcoila ~ 
labrum sm submentum 


metatentorina v vertex 


[78 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XIII 


79] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XIV 


80 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XIV 


VENTRAL ASPECT OF THE HEAD 


. Blepharida rhois. 

. Anoplitis gracilis. 

. Chelymorpha argus. 

. Pachymerus gleditsiae. 

. Eupsalis minuta. 

. Ithycerus noveboracensis. 
. Eurymycter fasciatus. 

. Rhinomacer pilosus. 

. Rhynchites bicolor. 

. Aitelabus analis. 

. Epicaerus imbricatus. 

. Lixus fimbriolatus. 

. Thecesternus humeralis. 
. Sphenophorus aequalis. 
. Platypus flavicornis. 

. Scolytus quadrispinosus. 
. Dendroctonus valens. 


LATERAL ASPECT OF THE HEAD 


. Tetracha carolina. 

. Cicindela formosa. 

. Calosoma calidum. 

. Harpalus erraticus. 

. Amphizoa lecontet. | 

. Omophron americanum. 
. Peltodytes 12-punctatus. 
. Cybister fimbriolatus. 

. Dineutes americanus. 


antacoila mé metatentorium 
antafossa oc occiput 
antacoria ol _ oculata 
cervepimeron os occipital suture 
cervepisternum pa  postgena 
compound eye pe  preclypeus 
clypealia pl _paracoila 
corpotentorium pn  pretentorina 
epicranial arm po postclypeus 
exoculata pr precoila 

front pi  pretentorium 
frontal ridge pil postcoila 

gula sm  submentum 
gula bar sn supratentorina 
labrum st supratentorium 
laminatentorium v vertex 


metatentorina 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


SLICKNEY HEAD-CAPSULE OF COLEOPTERA PLA LE, XLV 


81] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XV 


82 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


306. 
307. 
308. 
309. 
310. 
311. 
52. 
313. 
314. 
315. 
316. 
317. 
318. 
319. 
320. 
321. 
a2, 
323. 
324. 


ccp 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XV 
LATERAL ASPECT OF THE HEAD 


Hydraena marginicollis. 
Hydroscapha natans. 
Hydrous triangularis. 
Hydrophilus abtusatus. 
Platypsyllus castoris. 
Brathinus nitidus. 
Leptinus testaceus. 
Necrophorus carolinus. 
Clambus puberulus. 
Connophron fossiger. 
Molamba lunatic. 
Sienus flavicornis. 
Gastrolobium bicolor. 
Creophilus villosus. 
Tachinus fimbriatus. 
Aleochara lata. 
Pilopius lacustris. 
Fustiger fuchsi. 
Limulodes paradoxus. 


antacoila Ut laminatentorium 
antafossa mn metatentorina 
cervepimeron mt  metatentorium 
cervepisternum ol  oculata 
compound eye pa  postgena 
chitinized area pe preclypeus 
clypealia pl _ paracoila 
corpotentorium pn pretentorina 
epicranial arm po postclypeus 
front pr __ precoila 

frontal ridge pi pretentorium 
gula sm  submentum 
gula bar st | supratentorium 
labrum v vertex 


{82 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XV 


+ . 7 
| | hi oe : a 


83] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XVI 


83 


84 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XVI 


LATERAL ASPECT OF THE HEAD 


. Sphaerius politus. 

. Scaphidium quadriguttatum. 
. Sphaerites glabratus. 

. Hister memnonius. 

. Calopteron ierminale. 

. Photinus pyralis. 

. Phengodes plumosa. 

. Chauliognathus pennsylvanicus. 
. Collops nigriceps. 

. Trichodes nutalli. 

. Necrobia rufipes. 

. Hylecoetus lugubris. 

. Micromalthus debilis. 

. Cupes concolor. 

. Cephaloon lepturides. 

. Nacerda melanura. 

. Tomoxia bidentata. 

. Macrosiagon dimidiatum. 


. Epicauta marginata. 

. Eurystethus debilis. 

. Othinus sp. 
antacoila gub gula bar 
antafossa l labrum 
antacoria Ut laminatentorium 
cervepimeron mn metatentorina 
cervepisternum. mé metatentorium 
cervesternum. pe  preclypeus 
compound eye pl _ paracoila 
chitinized area pn  pretentorina 
clypealia po _postclypeus 
corpotentorium pt pretentorium 
epicranial arm pil postcoila 
front sm submentum 
frontal ridge st supratentorium 
gula v vertex 


(84 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XVI 


85] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XVII 


86 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


346. 
347. 
348. 
349. 
350. 
Sok: 
352. 
353. 
354. 
355. 
356. 
Eye 
358. 
359. 
360. 
361. 
362. 
363. 
364. 
365. 
366. 
367. 


aa 
af 
an 
ccp 
ces 
ce 
ch 
cl 
ct 
ea 
fe 
gu 
m 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XVII 
LATERAL ASPECT OF THE HEAD 


Pytho planus. 
Neopyrochroa flabellata. 
Macratria murina. 
Notoxus anchora. 
Zonantes fasciatus. 
Cebrio bicolor. 
Euthysanius lautus. 
Sandalus niger. 

Alaus oculatus. 
Tsorhipis ruficornis. 
Throscus chevrolatt. 
Chalcophora virginiensis. 
Psephenus lecontet. 
Helichus striatus. 
Stenelmis sinuata. 
Heterocerus undatus. 
Georyssus californicus. 
Eurypogon niger. 
Eucinetus morio. 
Cyphon ruficollis. 
Chelonarium errans. 
Dermestes lardarius. 


antacoila l labrum 
antafossa it laminatentorium 
antacoria mn metatentorina 
cervepimeron mé  metatentorium 
cervepisternum pe  preclypeus 
compound eye pl __ paracoila 


chitinized area pn pretentorina 
clypealia po postclypeus 
corpotentorium pt pretentorium. 
epicranial arm pu postcoila 
frontal ridge sm  submentum 
gula st supratentorium 
invagination v vertex 


(86 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


SLICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XVII 


87] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XVIII 


88 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XVIII 


LATERAL ASPECT OF THE HEAD 


. Byrrhus americanus. 

. Nosodendron unicolor. 

. Rhysodes americanus. 

. Tenebroides sinuatus. 

. Phenolia grossa. 

. Glischrochilus fasciatus. 

. Rhizophagus bipunctatus. 
. Phyconomus marinus. 

. Cucujus clavipes. 

. Hemipeplus marginipennis. 
. Languria mozardi. 

. Megalodacne fasciata. 

. Derodontus maculatus. 

. Anchicera ephippiata. 

. Byturus unicolor. 

. Mycetophagus punctatus. 
. Bothrideres geminatus. 

. Philothermus glabriculus. 
. Melanophthalma cavicollis. 
. Phymaphora pulchella. 

. Endomychus biguttatus. 


. Phalacrus politus. 
antacoila l¢  laminatentorium 
antafossa mn metatentorina 
antacoria mt metatentorium 
antacava od odontoidea 
cervepimeron pe  preclypeus 
cervepisternum pl _ paracoila 
compound eye pn pretentorina 
chitinized area po postclypeus 
clypealia pt  pretentorium 
corpotentorium pil postcoila 
epicranial arm sm  submentum 
frontal ridge st  supratentorium 
gula v vertex 
labrum 


[88 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


1 
i 
, 
1 
' 
1 
1 
! 
! 


Hey By nit 


ats! 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XVIII 


89] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XIX 


89 


90 


gu 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XIX 


LATERAL ASPECT OF THE HEAD 


. Hippodamia convergens. 
. Adalia bipunctatus. 

. Pseudocistela brevis. 

. Alobates pennsylvanica. 
. Tenebrio molitor. 

. Boros unicolor. 

. Arthromacra aened. 

. Hyporphagus sp. 

. Penthe obliquata. 

. Ptinus brunneus. 

. Sttodrepa panicea. 

. Bostrichus bicornis. 

. Lyctus planicollis. 

. Sphindus americanus. 
. Plesiocis cribrum. 

. Aphodius fimetarius. 

. Dichelonyx elongata. 

. Pelidnota punctata. 

. Strategus julianus. 

. Osmoderma eremicolla. 
. Trox suberosus. 

. Pseudolucanus capreolus. 
. Passalus cornutus. 


antacoila l labrum 
antafossa mn metatentorina 
antacoria mt metatentorium 
cervepimeron ol _—oculata 
cervepisternum pe  preclypeus - 
compound eye pl _ paracoila 
chitinized area pn pretentorina 
clypealia po _postclypeus 
corpotentorium pt pretentorium 
epicranial arm sm  submentum 
frontal ridge st supratentorium 
gula v vertex 


[90 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XIX 


- a ’ 
¢ = 
a | 
o ‘ * 
i \ 
s4s , 
p 
‘ 2 
‘ 
SS 
‘ e 2 
A. 
’ 
= 
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= 
4 
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. 
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! 
: 
; 
; 
i 
f f 
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91] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XX 


91 


92 


- 413. 
. 414, 
. 415. 
. 416. 
. 417. 
. 418. 
. 419. 
- 420. 
- 421. 
. 422. 
- 423, 
. 424. 
- 425. 
. 426. 
. 427. 
. 428. 
. 429. 
. 430. 
. 431. 
- 432. 
- 433. 
. 434, 
. 435. 


ccp 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XX 
LATERAL ASPECT OF THE HEAD 


Passalus cornutus. 
Parandra brunnea. 
Derobrachus brunneus. 
Spondylis buprestoides. 
Glycobius speciosus. 
Teiraopes tetraophthalmus. 
Donacia piscatrix. 
Syneia ferruginea. 
Criocerus asparagi. 
Cryptocephalus quadruplex. 
Chrysochus auratus. 
Leptinotarsa decemlineata 
Diabrotica 12-punctata. 
Blepharida rhois. 
Anoplitis gracilis. 
Chelymor pha argus. 
Pachymerus gleditsiae. 
Eupsalis minuta. 
Ithycerus noveboracensis. 
Eurymycter fasciatus. 
Rhinomacer pilosus. 


Rhynchites bicolor. 

Aittelabus analis. 

antacoila lt laminatentorium 
antafossa mn metatentorina 
antacoria mt  metatentorium 
antacava ol _oculata 
cervepimeron pa postgena 
cervepisternum pe _ preclypeus. 
compound eye pl _ paracoila 
chitinized area pn  pretentorina 
clypealia po _ postclypeus 
corpotentorium pr  precoila 
epicranial arm pt pretentorium 
frontal ridge sm  submentum 
gula st supratentorium 
labrum v vertex 


[92 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


v Kathy V# 


Hr @r-- Hv ff 
x a L 
V& A 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XX 


eG. Gee 


hatte 


A at 
ee ‘ 
4 ; lJ 
+ F “ 
Lt dve ’ 
~ if 
oT] 5 
rte : 3% 
, 
a0 ‘ 
7 aw, 


eet. 


93] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XXI 


93 


94 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


436. 
437. 
438. 
439, 
. Platypus flavicornis. 

. Scolytus quadrispinosus. 
. Dendrocionus valens. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XXI 
LATERAL ASPECT OF THE HEAD 


Epicaerus imbricatus. 
Lixus fimbriolatus. 
Thecesternus humeralis. 
Sphenophorus aequalis. 


ENDOSKELETON OF THE HEAD 


. Hypothetical type. 

. Tetracha carolina. 

. Cicindela formosa. 

. Calosoma calidum. 

. Harpalus erraticus. 

. Amphizoa lecontei. 

. Omophron americanum. 
. Peltodytes 12-punctata. 
. Cybister fimbriolatus. 

. Dineutes americanus. 

. Hydraena marginicollis. 
. Hydroscapha natans. 

. Hydrous triangularis. 

. Hydrophilus obtusatus. 
. Platypsyllus castoris. 


antafossa mn wmetatentorina 
antacava mt  metatentorium 
cervepimeron od odontoidea 
cervepisternum pl paracoila — 
compound eye pn _ pretentorina 
clypealia pr precoila 
corpotentorium pt pretentorium 
epicranial arm pil postcoila 
invagination sm  submentum 
labrum sn supratentorina 
laminatentorium st supratentorium 


[94 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


SrICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XXI 


% 


95] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XXII 


95 


96 ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XXII 
ENDOSKELETON OF THE HEAD 


Fig. 458. Brathinus nitidus. 
Fig. 459. Leptinus testaceus. 
Fig. 460. Necrophorus carolinus. 
Fig. 461. Clambus puberulus. 
Fig. 462. Connophron fossiger. 
Fig. 463. Stenus flavicornis. 

Fig. 464. Gastrolobium bicolor. 
Fig. 465. Creophilus villosus. 
Fig. 466. Tachinus fimbriatus. 
Fig. 467. Aleochara lata. 

Fig. 468. Pilopius lacustris. 

Fig. 469. Limulodes paradoxus. 
Fig. 470. Sphaerius politus. 

Fig. 471. Scaphidium quadriguttatum. 
Fig. 472. Sphaerites glabratus. 
Fig. 473. Hister memnonius. 
Fig. 474. Calopieron terminale. 
Fig. 475. Photinus pyralis. 

Fig. 476. Phengodes plumosa. 
Fig. 477. Chauliognathus pennsylvanicus. 
Fig. 478. Collops nigriceps. 

Fig. 479. Trichodes nutalli. 

Fig. 480. Necrobia rufipes. 

Fig. 481. Hylecoetus lugubris. 


af  antafossa mn metatentorina 
an  antacoria mt metatentorium 
av antacava od odontoidea 

ccp cervepimeron pl paracoila — 
ccs cervepisternum pn  pretentorina 

ce compound eye pr precoila 

ct —_ corpotentorium pt pretentorium 
gub gular bar pil  postcoila 

l labrum sn supratentorina 
im invagination st supratentorium 


lt laminatentorium 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


NY) \ 


ait 
ave 

Wii) 

(Ny hy 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XXII 


97) 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XXIII 


98 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XXIII 


ENDOSKELETON OF THE HEAD 


. Cupes concolor. 


Cephaloon lepturides. 


. Nacerda melanura. 


Tomoxia bidentata. 
Macrosiagon dimidiatum. 
Epicauta marginata. 
Eurystethus debilis. 


. Othnius sp. 
. Pytho planus. 


Neopyrochroa flabellata. 


. Macratria murina. 
. Notoxus anchora. 
. Zonantes fasciatus. 


Cebrio bicolor. 


. Euthysanius lautus. 

. Sandalus niger. 

. Alaus oculatus. 

. Isorhipis ruficornis. 

. Throscus chevrolati. 

. Chalcophora virginiensis. 
. Psephenus lecontet. 

. Helichus striatus. 3 

. Stenelmis sinuata. 

. Heterocerus undatus. 


antafossa lt  laminatentorium 
cervepimeron mn metatentorina 
cervepisternum mt  metatentorium 
cervesternum od _odontoidea 
compound eye pl  paracoila 
chitinized area pr precoila 
corpotentorium pt pretentorium 
epicranial arm pil postcoila 
invagination st supratentorium 
labrum 


[98 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


SIlUICKNE Y HEAD-CAPSULE OF COLEOPTERA PLATE XXIII 


99] 


THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 


PLATE XXIV 


100 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XXIV 


ENDOSKELETON OF THE HEAD 


. Georyssus californicus. 

. Eurypogon niger. 

. Eucinetus morio. 

. Cyphon ruficollis. 

. Chelonarium errans. 

. Dermestes lardarius. 

. Byrrhus americanus. 

. Nosodendron unicolor. 

. Rhysodes americanus. 

. Tenebroides sinuatus. 

. Phenolia grossa. 

. Glischrochilus fasciatus. 

. Rhizophagus bipunctatus. 
- Phyconomus marinus. 

. Cucujus clavipes. 

. Hemipeplus marginipennis. 
. Languria mozardi. 

. Megalodacne fasciata. 

. Derodontus maculatus. 

. Anchicera ephippiata. 

. Byturus unicolor. 

. Mycetophagus punctatus. 
. Bothrideres geminatus. 

. Philothermus glabriculus. 
. Melanophthalma cavicollis. 
- Phymaphora pulchella. 


. Endomychus biguttatus. 
antafossa mn metatentorina 
cervepimeron mé metatentorium 
cervepisternum od _odontoidea 
cervisternum pl paracoila 
compound eye fr precoila 
corpotentorium pi pretentorium 
invagination pil postcoila 
labrum st supratentorium 


laminatentorium 


[100 


VOLUME VIII 


ILLINOIS BIOLOGICAL MONOGRAPHS 


PLATE XXIV 


CAPSULE OF COLEOPTERA 


HEAD- 


SLICKNEY 


101] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 101 


PLATE XXV 


102 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Vig. 
Fig. 
Fig. 
Fig. 


533. 
534. 
535, 
536. 
537. 
538. 
539. 
540. 
541. 
542. 
543. 
544, 
545. 
546. 
547. 
548. 
549. 
550. 
551. 
552. 
553. 
. Trox suberosus. 

. Pseudolucanus capreolus. 
556. 
557. 
558. 


ccp 


ccs 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XXV 
ENDOSKELETON OF THE HEAD 


Phalacrus politus. 
Hippodamia convergens. 
Adalia bipunctata. 
Pseudocistela brevis. 
Alobates pennsylvanica. 
Tenebrio molitor. 
Boros unicolor. 
Arthromacra aenea. 
Hyporphagus sp. 
Penthe obliquata. 
Ptinus brunneus. 
Sitodrepa panicea. 
Bostrichus bicornis. 
Lyctus planicollis. 
Sphindus americanus. 
Plesiocis cribrum. 
Aphodius fimetarius. 
Dichelonyx elongata. 
Pelidnota punctata. 
Strategus julianus. 
Osmoderma eremicola. 


Passalus cornutus. 
Parandra brunnea. 
Derobrachus brunneus. 


antafossa mn metatentorina 
cervepimeron mé metatentorium 
cervepisternum od odontoidea 
cervisternum pl  paracoila 
compound eye po postclypeus 
corpotentorium pr precoila 
epicranial arm pt pretentorium 
invagination pil postcoila 
labrum sm submentum 


laminatentorium st supratentorium 


[102 


ILLINOIS BIOLOGICAL MONOGRAPHS VOLUME VIII 


Ay 


STICKNEY HEAD-CAPSULE OF COLEOPTERA PLATE XXV 


103] THE HEAD-CAPSULE OF COLEOPTERA—STICKNEY 103 


PLATE XXVI 


104 


Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 


ILLINOIS BIOLOGICAL MONOGRAPHS 


EXPLANATION OF PLATE XXVI 
ENDOSKELETON OF THE HEAD 


. Spondylis buprestoides. 

. Glycobius speciosus. 

. Tetraopes tetraophthalmus. 
. Donacia piscatrix. 

. Syneta ferruginea. 

. Criocerus asparagi. 


. Cryptocephalus quadruplex. 


. Chrysochus auratus. 


. Leptinotarsa decemlineata. 
. Diabrotica 12-punctata. 
. Blepharida rhois. 


. Anoplitis gracilis. 

. Chelymor pha argus. 

. Pachymerus gleditsiae. 

. Eupsalis minuta, 

. Ithycerus noveboracensis. 
. Eurymycter fasciatus. 

. Rhinomacer pilosus. 

. Rhynchites bicolor. 

. Attelabus analis. 


. Epicaerus imbricatus. 

. Lixus fimbriolatus. 

. Thecesternus humeralis. 

. Sphenophorus aequalis. 

. Platypus flavicornis. 

. Scolytus quadrispinosus. 

. Dendroctonus valens. 
antafossa mt  metatentorium 
cervepisternum od odontoidea 
compound eye pl paracoila 
corpotentorium pr precoila 
epicranial arm pi pretentorium 
invagination pill postcoila 
laminatentorium st supratentorium 


metatentorina 


[104 


VOLUME VIII 


OIS BIOLOGICAL MONOGRAPHS 


= 
/ 


WELT N 


PLATE XXVI 


HEAD-CAPSULE OF COLEOPTERA 


SLICKNEY 


ch ee 


oc Dey te 
“Ud wae 


ANY 
Wnt 


val AMEN 


Wy 
LRT 
i My} Wins MER 
FC ty 


NT ta 
if Ney 


Se he 


Ny 
fe 


ees 


aA 


A ati 


VERSITY OF ILLINOIS-URBANA 


WN 


3 0112 065097260 


